# iMac onboard DAC vs. external?



## MrHeuristic

First, I'd like to say hi — this is my first post. I'm looking to make my first foray into headphones. As a college student with just a pair of Logitech Z2300 computer speakers, I'm excited for the upgrade to a headphone amp and headphones. 
   
  I've already purchased a TU-882 amp (I know, I know, tubes, I could probably have gotten a SS with more accurate amplification for cheaper. I thought a kit would be fun though, and it's not OTL) and I'm looking to pair it with the AKG K702.
   
  Now, pretty much everywhere else on Head-Fi, I see recommendations for expensive DACs. Some members even suggest spending the majority of one's budget on a fancy DAC, and claim a massive difference in sound quality. 
  However, from my short reading time in Sound Science, I've noticed that there's a massive amount of confirmation bias, wish thinking, and unevidenced poetic ramblings in the audiophile community (lots of parallels to the religious community, actually).
   
  So, I'd like to ask here: *is there an objective, audible difference between an external DAC and the internal DAC in, say, my iMac*?
  More specifically, has anyone else here with both an iMac (or Mac Mini, MBP, or Airport Express) and a DAC done any blind ABX testing between the onboard DAC in the Apple computer and the external DAC? 
   
  I'm already out $600 for the headphone and amplifier, and if I can avoid buying another component on my college budget, I will.


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## stv014

Quote: 





> Originally Posted by *MrHeuristic* /img/forum/go_quote.gif
> 
> So, I'd like to ask here: *is there an objective, audible difference between an external DAC and the internal DAC in, say, my iMac*?


 
   
  It is hard to tell without having reliable and detailed measurements of the iMac DAC available. The quality of onboard audio is quite variable.


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## bigshot

The DACs in Apple products have always been consistently top quality. If there would be any measurable improvement in going to an external DAC it would certainly be beyond the threshold of human perception.


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## nick_charles

Quote: 





stv014 said:


> It is hard to tell without having reliable and detailed measurements of the iMac DAC available. The quality of onboard audio is quite variable.


 
   
  Indeed ! - my old Lenovo laptop had something like an -8db cliff at 10k 
   
  Quote: 





bigshot said:


> The DACs in Apple products have always been consistently top quality. If there would be any measurable improvement in going to an external DAC it would certainly be beyond the threshold of human perception.


 
   
  Generally yes but it does not hurt to do some measurements. All one needs is a decent ADC connected to a 2nd computer run the analog outputs from source A and source B into it, align, trim  and compare the results. I've done this with my CD players and found surprising differences sometimes (admittedly normally output levels)


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## bigshot

The Mac Mini was designed to be an AV machine out of the box. Apple has always been focused on sound quality. I mastered CDs on an ancient 8500 AV and I run 5:1 sound out of my Mac Mini. It's as good as it gets.


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## nick_charles

Quote: 





bigshot said:


> The Mac Mini was designed to be an AV machine out of the box. Apple has always been focused on sound quality. I mastered CDs on an ancient 8500 AV and I run 5:1 sound out of my Mac Mini. It's as good as it gets.


 
   
  Sorry to seem contrary but the OP was after empirical tests or objective measurements, remember where we are !
   
  I love the sound out of my $90 DAC/amp but that is not data either just another anecdote.


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## TMRaven

Recent apple computers have great dacs.  I'd be hard-pressed to tell the difference between the onboard audio of my 09 iMac and HRT Music StreamerII/ ODAC.  The most benefit you'll get from an external dac at this point would be a more efficient external amp and elimination of any computer noise.


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## MrHeuristic

Quote: 





tmraven said:


> ...and elimination of any computer noise.


 
  I have noticed that on my iMac, when plugging in cheap earbuds (some skullcandy in-ears, they're all I have to test it until my K702 gets in) to the headphone jack, I can hear an audible white noise or hiss when the iMac is amplifying and nothing is playing. After about a minute or two with no sound output from the OS, I can hear the iMac stop amplifying sound, and the hiss goes away. If I play anything in the OS, the hiss again comes back moments before the audio starts playing. I believe this is called a high noise floor? 
   
  I don't notice it on my Logitech speakers, though, so I'm wondering if it will be noticeable if I directly amplify the iMac's output and use some better headphones. If, when my amp and K702's arrive, and the high noise floor is still a problem, an external DAC will prevent this?


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## TMRaven

That is a high noise floor, yes.  It has more to do with the amp of the imac and not its dac most likely, and is also a result of the earbuds' very high efficiency.  Lots of very expensive 'audiophile' amps can exhibit the same results with very efficient in-ears as well.  I was moreso talking about any kind of electrical interference that you might hear when say, scrolling on a safari window or opening applications etc.


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## MrHeuristic

Quote: 





tmraven said:


> That is a high noise floor, yes.  It has more to do with the amp of the imac and not its dac most likely


 
  In that case, if I were to skip buying a DAC for my setup, how would I isolate the iMac's DAC output from its internal amplifier?
   
  My amp has RCA inputs and a 1/8" line in. If I were to connect the iMac's headphone jack directly to the line in, would the amplifier be amplifying the already-amplified signal from within the iMac, or just the bare DAC output? If not the latter, how would I achieve that?


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## bigshot

The Mac Mini has analogue line out. Just connect that to your amp and you'll have no problem. You don't need to use the headphone jack at all.


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## MrHeuristic

Ah, so it appears the headphone jack on the iMac is also the line out, even when using regular 3.5mm cable (not optical mini Toslink)? From the spec page at Apple, I get this: 


> *Line/Headphone output*
> 
> The headphone output is automatically selected for audio output if no external S/PDIF optical digital output device is detected. The headphone output supports a stereo data stream at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. The headphone output volume can be adjusted from 0.0 dB to -64 dB.


 
   
  So, I guess my next question is, if I'm connecting to my amplifier with a regular old 3.5mm cable, do I set my iMac to full volume? How do you do this with your Mini?


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## bigshot

The Mini has a true analogue line out too.


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## MrHeuristic

Quote: 





bigshot said:


> The Mini has a true analogue line out too.


 
   
  Yes, but when you amplify that, do you set the volume output on the Mac Mini — in the operating system itself — to full volume? minimum volume? Or does it not matter?


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## bigshot

You can adjust it in iTunes. It doesn't matter where you set it. I keep it about 75% so I have room to turn it up from my iPhone if I want.


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## MrHeuristic

Sorry, I guess I'm still a bit confused. Here's a screenshot of my sound preferences when I have a 3.5mm cable plugged into my iMac.
   
  See how there's still a volume control on the output? To me, that means that the iMac is still amplifying the sound, rather than outputting a base line-out. And again, I will be going iMac —> Tube amp —> K702, not directly into the headphones.


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## bigshot

It isn't amplified. Full blast is normal line level. The sound is just reduced when you use the volume control in iTunes. It's all software, not hardware.


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## PurpleAngel

Quote: 





mrheuristic said:


> First, I'd like to say hi — this is my first post. I'm looking to make my first foray into headphones. As a college student with just a pair of Logitech Z2300 computer speakers, I'm excited for the upgrade to a headphone amp and headphones.
> I've already purchased a TU-882 amp (I know, I know, tubes, I could probably have gotten a SS with more accurate amplification for cheaper. I thought a kit would be fun though, and it's not OTL) and I'm looking to pair it with the AKG K702.
> Now, pretty much everywhere else on Head-Fi, I see recommendations for expensive DACs. Some members even suggest spending the majority of one's budget on a fancy DAC, and claim a massive difference in sound quality.
> However, from my short reading time in Sound Science, I've noticed that there's a massive amount of confirmation bias, wish thinking, and unevidenced poetic ramblings in the audiophile community (lots of parallels to the religious community, actually).
> ...


 
  Try the Hifimediy Sabre USB-DAC, $45 plus $5-$29 shipping, uses the same receiver chip and DAC chip as the ODAC ($150). I'm not saying the Hifimediy Sabre matches the ODAC,
  but for only $52 (Hifimediy Sabre), it's something to try for a low cost.
   
  Also here is a low cost "Premium' cable for connecting the USB-DAC to your tube amp.
  http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10218&cs_id=1021815&p_id=5596&seq=1&format=2


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## MrHeuristic

Quote: 





bigshot said:


> It isn't amplified. Full blast is normal line level. The sound is just reduced when you use the volume control in iTunes. It's all software, not hardware.


 
   
  Got it. Thanks for your help.
   
  If the headphone jack on the iMac and Mac Mini serve dual purpose as level line outs, why doesn't the headphone jack on the iPhone/iPod do the same? I'm fairly certain that LOD connectors are required to get a true line level from those.


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## PurpleAngel

Quote: 





mrheuristic said:


> Got it. Thanks for your help.
> 
> If the headphone jack on the iMac and Mac Mini serve dual purpose as level line outs, why doesn't the headphone jack on the iPhone/iPod do the same? I'm fairly certain that LOD connectors are required to get a true line level from those.


 
  The line-out/headphone jacks on the iMac and Mac Mini are more like line-outs that pretend to be headphone jack.
  also I think there is some reason that those line-outs need to have a high impedance
   
  I believe the headphone jacks on the iPhone/iPod are really just expected to be plugged into low Ohm headphones, which means their headphone jack needs to be really low Ohm


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## iEar

Hi, I'm coming a few months late to this thread I know but hope someone will see the questions.
   
  Did you find a way to get pure DAC signal out of the iMac to the amp?
   
  I've been using an optical cable from the output jack on the back of the iMac
  but find that the volume can still be adjusted with iTunes which to my limited understanding
  would mean the iMac amp is still processing the signal. Would this be correct?
   
  Have you had any other flashes of inspiration regarding getting sound out of the iMac?
   
  Cheers,
  Mark.


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## bigshot

Quote: 





iear said:


> I've been using an optical cable from the output jack on the back of the iMac
> but find that the volume can still be adjusted with iTunes which to my limited understanding
> would mean the iMac amp is still processing the signal. Would this be correct?


 
   
  No, that is incorrect. The signal is still digital. It's just being attenuated in the digital domain. (read volume level adjusted digitally). No sound quality loss.


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## GSARider

Interesting thread, is the conclusion that an amp plugged directly to a mac is just as good in terms of listening to a high priced Dac?


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## bigshot

Depending on the headphones you're using, you may not even need the amp.


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## iEar

Thanks bigshot! I've re-read the thread and now have a much better understanding of
  the reasons for your answer! Do you have any info on which would be a better way of
  connecting the iMac to the AV receiver? I use the optical cable now but wonder if
  a the 3.5mm jack to RCA would be a better set up? Or, no difference? I'd test it
  but I don't have such a cable! Thanks for you info in the posts above! much appreciated


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## bigshot

Optical cable or HDMI are best.


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## GSARider

HD800's, Amperiors, Momentum's mainly.


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## bigshot

check the specs on your cans. if they're less than 100 ohms, I'm told you should be good to go. above that, you might want a cheap amp.


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## GSARider

Well up to 300 ohms, don't need to check, I already know...


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## OldHarbourGreen

Joining the thread late.  iMac specs from Apple below.  S/PDIF has higher SNR and lower distortion.       *I/O ports*  *1. Headphone port*

 *Line/headphone output *
 The headphone output is automatically selected for audio output if no external S/PDIF optical digital output device is detected. The headphone output supports a stereo data stream at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. The headphone output volume can be adjusted from 0.0 dB to -43.0 dB.

 During playback of a 1 kHz sine wave at -3 dBFS voltage level, 24-bit sample depth, 44.1 kHz output sample rate, 100 k load (unless otherwise specified), the audio output has the following nominal specifications:


 Jack type: 3.5 mm (1/8-inch) stereo combo
 Maximum output voltage: 1.4 VRMS (+5.15 dBu)
 Output impedance: <24 ohms
 Frequency response: 20 Hz to 20 kHz, +0.5 dB/-3 dB
 Signal-to-noise ratio (SNR): >90 dB
 Total harmonic distortion + noise (THD+N): <-80 dB (0.007%)
 Channel separation: >85 dB

   

 *S/PDIF optical digital output *
 The S/PDIF (Sony/Philips Digital Interface Format) optical digital output is automatically selected when an S/PDIF optical digital output device is detected on the external combination audio port. The S/PDIF optical digital output supports pulse-code modulation (PCM) and Arc Consistency Algorithm #3 (AC-3) audio formats with the following stereo data stream characteristics:


 PCM: 16, 20, or 24 bits per sample at sample rates of 44.1 kHz, 48 kHz, or 96 kHz
 AC-3: 16 bits per sample at sample rates of 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz

  The S/PDIF optical output channel status conforms to International Electrotechnical Commission (IEC) 60958-3 consumer mode digital audio.

 During playback of a 1 kHz sine wave (S/PDIF output format at 0 dBFS output level, 44.1 kHz sample rate, 24-bit sample depth, unless otherwise specified), the digital audio output has the following nominal specifications:


 Jack type: 3.5 mm (1/8-inch) stereo combo
 Digital audio signal-to-noise ratio (SNR): >130 dB
 Digital audio total harmonic distortion + noise (THD+N): <-130 dB (0.00003%)


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## Currawong

I'm not sure how they derive the S/N ratio of a digital output, as that is totally different to the S/N ratio of an analog output. 
   
  Anyhow, here is a quick measurement of the headphone output of my MacBook Pro versus the the analogue loopback of the ULN-2 which I used for the measurement. These shouldn't be taken as professional measurements, just as a comparison. The measurements were done at around -6dB. I think a 20-40 dB difference in the amount of distortion at the levels shown is significant enough. 
   
   

   

   
   
  To answer the OPs question though: You can do better than the analogue output of a Mac by a considerable margin. I haven't compared DACs with the TU-882R, but I'd say a basically decent DAC would benefit it.


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## nick_charles

Quote: 





oldharbourgreen said:


> Joining the thread late.  iMac specs from Apple below.  S/PDIF has higher SNR and lower distortion.       *I/O ports*  *1. Headphone port*
> 
> *Line/headphone output *
> The headphone output is automatically selected for audio output if no external S/PDIF optical digital output device is detected. The headphone output supports a stereo data stream at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. The headphone output volume can be adjusted from 0.0 dB to -43.0 dB.
> ...


 
   
   
  These are frankly pretty poor, certainly worse than red book requires and done with a 24 bit signal no less and at -3db which makes me think it may clip at full whack - compare that to 
   
   
http://www.stereophile.com/content/marantz-cd5004-cd-player-marantz-cd5004-cd-player-measurements - a budget CD player
   
http://www.ebay.com/itm/Professional-HiFiMAN-EF5-Headphone-Amplifier/170696111860 - a cheapo HK made DAC/headphone amp or basically any number of low cost eBay Chinese DAc/amps
   
  Of course this does not mean it sounds bad in any way but spec wise it is unimpressive !


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## jaddie

Quote: 





nick_charles said:


> These are frankly pretty poor, certainly worse than red book requires and done with a 24 bit signal no less and at -3db which makes me think it may clip at full whack - compare that to
> 
> 
> http://www.stereophile.com/content/marantz-cd5004-cd-player-marantz-cd5004-cd-player-measurements - a budget CD player
> ...


 
  Red book is a set of CD specs that include nothing about audio performance.  It's formatting, data structure, etc.  There are no red book audio requirements.  
   
  All D/As clip at "full whack".  None would clip at -3dB.  
   
  Careful when comparing a measured noise figure to a noise spectrum plot.  The plot will always look much better because the measured noise is a sum of the entire bandwidth, whereas the spectrum plot is a measurement based on the maximum resolution bandwidth, which is very small.  There's also nothing about weighting, noise shaping, etc.  
   
  The eBay DAC specs are unrealistic, highly doubtful, and unprovable by almost any buyer.  Not to say it's not "good", just likely exaggerated.  
   
  The difference between the Mac and the other devices would likely be too small to be a audible with any actual audio recording, though it may not measure as well.


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## nick_charles

Quote: 





jaddie said:


> Red book is a set of CD specs that include nothing about audio performance.  It's formatting, data structure, etc.  There are no red book audio requirements.
> 
> *CD theoretically anyway has a SNR of about 96db the Apple onboard device at 90db is around 15 bits, probably not noticeable but certainly not state of the art, in truth you are unlikely to notice the difference between 14 bits and 16 bits except at absurd volume levels like the Meyer and Moran study*
> 
> ...


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## bigshot

jaddie said:


> The difference between the Mac and the other devices would likely be too small to be a audible with any actual audio recording, though it may not measure as well.




That's really all that needs to be said. When the specs on a player exceed the specs on our ears by a fair margin, there's no need to throw out numbers any more.


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## jaddie

Quote: 





nick_charles said:


> *CD theoretically anyway has a SNR of about 96db the Apple onboard device at 90db is around 15 bits, probably not noticeable but certainly not state of the art, in truth you are unlikely to notice the difference between 14 bits and 16 bits except at absurd volume levels like the Meyer and Moran study*


 
  Yes, but no 16 bit device ever does the theoretical 96dB without quite a bit of trickery like oversampling DACs and noise shaping. But it doesn't matter because if you hit it with 16 bit audio data you'll never get 96dB anyway, and you wouldn't want to because you do want that data dithered, and that alone will kick you down to 93 or less.  If the audio was digitized at 16 bits there'll be 3dB at least of least significant bit jitter.  And if digitized at 24 bits, the conversion to 16 should never just be truncation, sort of defeats the purpose.  So 90dB, real world, is about right for anything.  The stuff that measures better isn't measured with a digitized analog signal, and yes the measurements are real, but you have to consider the noise floor of real audio material too, and noise-shaping, over-sampling DACs can't help that.  There are better measuring DACS, but that doesn't mean they'll sound better.  And, 96dB or even 90dB is pretty much more that we need.
   
  quote: "*Interesting, then why do so many engineers seem to insist on hitting the end-stops if it just leads to distortion 
	

	
	
		
		

		
		
	


	




"*
   
  It's the loudness war, and the end stops they are actually hitting aren't in the DAC, they're in the data processed by some sort of DSP that may involve clipping or hard limiting.  Yes, it's nasty, but until people stop buying, and start returning music that's so loud its distorted for their money back, engineers (technically, producers) will keep making it.
   
   
*quote: "**Hmmm, I've seen far more "optimistic" specs on some mainstream gear (add another couple of zeros) and some like the Benchmark stuff seems to have measurements to back it up, the one positive thing about Stereophile being that they do actually measure stuff, not turntables of course.... wonder why *




  
 *But yeah the general lack of actual measurements is highly annoying !"*
  
  Yup, sure is.  And yes, there are lots of things that measure better.  Like I said, it's not all real once you start playing audio though.  It might be me being cranky and old, but I tend to ignore DACs that measure better than theoretical because once you shove real digital audio into it instead of computer generated test data you're back to 16 bits again.  Sort of pointless, but since so-called 24 bit ADCs behave like 18-20 bit ADCs, and when audio gets shoved up to the top end and squashed there, the discussion is really academic.  Yes, it's fun to bash Apple, but frankly, they put pretty decent audio into their devices, on average way better than the integrated PC sound junk. And there are some VERY smart people in the audio department there.  It's likely to get even better.


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## IA64

I own an iMac 27' core i7. I've always thought the sound quality is decent compared to other sound cards. 
   
  When I got the JH16's the bottleneck was the sound card in my setup. I added a DAC/AMP ( Yulong D100 MKII) connected to S/PDIF and the difference is huge. I mean very huge.
   
  1 - There is no audible white noise or hiss when nothing is playing no matter how loud the volume is
   
  2- Bass is much more controlled with rumble, not bloated when volume is high
   
  3 - Soundstage is definitely wider 
   
  4 - Upsampling/downsampling and option to dynamically switch the sample rate and bit depth depending on the track playing.
   
  5- No electrical interference ( HDD, ground or USB device noise )


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## bigshot

If you were getting hiss and grounding interference at normal listening volumes, even very loud ones, there is something wrong with your iMac. If it's still under warranty, I would take it to the Apple store and get them to check it out.


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## Currawong

You get a fair bit of beeping and buzzing from the headphone/line out of Macs. This is normal. It's much worse with very sensitive IEMs such as most customs. It doesn't show up in measurements because the input impedance of measuring equipment is 50 Ohms or greater and some sounds like buzzing comes randomly.


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## bigshot

My Mac Mini and iMac 29 are stone silent. I can crank the volume way up with my cmoy and it's still clean. I have mirrordoor PowerMacs too and those are as clean as clean can be. Perhaps other models have higher defect rates. What model of Mac do you have?


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## TMRaven

I can also vouch that the headphone out of my iMac is very clean as well, it was even clean with the very sensitive Denon D2000 when I used to have that.
   
  The only time I get a good amount of noise from the iMac's headphone out is if I hook it up to a my stereo receiver and turn the volume up quite a bit on the receiver for the speakers.  The sheer magnitude of the receiver's gain really amplifies the noise of the iMac's headphone out, but near maxing the iMac's sound out and using less juice on the speaker amp solves that.


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## Currawong

Quote: 





bigshot said:


> My Mac Mini and iMac 29 are stone silent. I can crank the volume way up with my cmoy and it's still clean. I have mirrordoor PowerMacs too and those are as clean as clean can be. Perhaps other models have higher defect rates. What model of Mac do you have?


 
   
  I'm listening now with the XBA-30s and don't hear anything. However, CIEMs tend to be much more sensitive. I don't have anything as that here at the moment to test with though. I do remember managing to get computer noise from it at one point, though I can't remember with what. Possibly it was with an amp.


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## IA64

Quote: 





bigshot said:


> If you were getting hiss and grounding interference at normal listening volumes, even very loud ones, there is something wrong with your iMac. If it's still under warranty, I would take it to the Apple store and get them to check it out.


 
   
  I am afraid to say that there isn't anything wrong with my iMac, that's been the case with my two older iMacs as well. It's completely normal. With high sensitivity IEMs like Shure SE535 and JH16,
   
  One important thing to remember is that this is mostly noticeable under BootCamp and not OSX because under the latter, the sound card goes into indle state after few seconds of silence whereas under Bootcamp, the soundcard driver is always active.


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## bigshot

Are you talking about an impedance mismatch?


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## bigshot

I did a little googling and determined that you are indeed talking about a mismatch with low impedance earphones. That isn't the fault of the DAC. It isn't even really the fault of the Mac any more than it is the earphones. Either select a headphone that matches well with the Mac, or use a headphone amp and the problems will be solved.
   
  That's why I was completely confused by people saying that the Mac had bad sound. With my Sennheiser headphones, the output is pretty near perfect. When I amp it, I can crank it way up and it's extremely clean.


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## IA64

Quote: 





bigshot said:


> I did a little googling and determined that you are indeed talking about a mismatch with low impedance earphones. That isn't the fault of the DAC. It isn't even really the fault of the Mac any more than it is the earphones. Either select a headphone that matches well with the Mac, or use a headphone amp and the problems will be solved.
> 
> That's why I was completely confused by people saying that the Mac had bad sound. With my Sennheiser headphones, the output is pretty near perfect. When I amp it, I can crank it way up and it's extremely clean.


 
   
  That doesn't mean that an external DAC doesn't add much.


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## bigshot

The DAC built into Mac products is comparable to stand alone DACs. Even if the standalone DAC had significantly better specs, it still wouldn't be audible, because the improvements would all lie beyond the range of human perception.
   
  One of the truths I've found after a few decades in this hobby is that if you have a problem with your sound quality, it's best to 1) isolate the problem 2) identify its source and 3) attack the problem directly. I know a lot of people just keep upgrading randomly hoping that eventually the upgrades will make a difference, but I've never found that approach to be at all effective.
   
  If it ain't broke, don't fix it!


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## IA64

Quote: 





bigshot said:


> The DAC built into Mac products is comparable to stand alone DACs. Even if the standalone DAC had significantly better specs, it still wouldn't be audible, because the improvements would all lie beyond the range of human perception.
> 
> One of the truths I've found after a few decades in this hobby is that if you have a problem with your sound quality, it's best to 1) isolate the problem 2) identify its source and 3) attack the problem directly. I know a lot of people just keep upgrading randomly hoping that eventually the upgrades will make a difference, but I've never found that approach to be at all effective.
> 
> If it ain't broke, don't fix it!


 
   
  The problem is that you don't know it's broken until you try something new.


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## bigshot

The way you find out is to take your headphones with you to other folks' houses and listen to the same recording on a variety of systems. If your system sounds worse than the rest, you need to get to work figuring out what's wrong.

Imagine if you decided you were going to have a mechanic put a new transmission in your car, even though you'd never had any problem with your transmission. Perhaps it might make you accellerate a little faster... But the odds are, if a transmission is broken, you would know about it, and replacing it randomly is a waste of money.

When digital audio is broken, it artifacts like crazy. It isn't a subtle thing. Even cheap modern DACs are capable of performing up to and beyond the limits of human hearing. Replacing a DAC without ever identifying anything wrong with the old one is a waste of money.

An iPod, iPhone or iMac is such a small, simple and elegantly designed thing, and its onboard sound quality is so high, I see absolutely no reason to junk it up by attaching more cables and battery operated boxes to do basically the same thing.


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## IA64

Quote: 





bigshot said:


> The way you find out is to take your headphones with you to other folks' houses and listen to the same recording on a variety of systems. If your system sounds worse than the rest, you need to get to work figuring out what's wrong.
> 
> Imagine if you decided you were going to have a mechanic put a new transmission in your car, even though you'd never had any problem with your transmission. Perhaps it might make you accellerate a little faster... But the odds are, if a transmission is broken, you would know about it, and replacing it randomly is a waste of money.
> 
> ...


 
   
  Well the iMac onboard DAC is superior to its All-in-one desktop rivals but a $600 DAC definitely improves the performance. The issue is whether you notice it or not. I personally can't hear any difference between a 256-320kbps MP3 and a loseless audio format but some people do.
   
  I tried both Shure SE535 and JH16 from analogue output of my Mac and a DAC definitely improved the sound by a big margin. 
   
  Most noticeable difference was the Bass, more energetic, punchier and very well controlled. iMac onboard DAC doesn't do well with high sensitivity IEMs. Fortunately my DAC has two headphone output one for low and another one for high impedance phone.
   
  The thing is that there isn't much you can do with desktop rigs. Your best bet is to bypass the sound card completely.
   
  Heck, even bitperfect or Asio under Windows make a difference let alone the fact that you can play with the sampling rate the way you want with an external DAC.
   
  My 2 cents.


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## bigshot

Quote: 





ia64 said:


> I tried both Shure SE535 and JH16 from analogue output of my Mac and a DAC definitely improved the sound by a big margin.
> 
> Most noticeable difference was the Bass, more energetic, punchier and very well controlled. iMac onboard DAC doesn't do well with high sensitivity IEMs. Fortunately my DAC has two headphone output one for low and another one for high impedance phone.


 
   
  You're attributing the difference in sound to the DAC, but it isn't the DAC. It's the headphone amp. You have an impedance mismatch with the particular earphones you're using. With other headphones, there would be no problem at all, and with your IEMs, a simple cmoy headphone amp would probably make the exact same improvement as completely bypassing the iMac's DAC.
   
  The DACs in Macs sound just as good as standalone DACs. The specs for them extend beyond the range of human hearing. No need to replace a Mac's DAC.


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## IA64

Quote: 





bigshot said:


> You're attributing the difference in sound to the DAC, but it isn't the DAC. It's the headphone amp. You have an impedance mismatch with the particular earphones you're using. With other headphones, there would be no problem at all, and with your IEMs, a simple cmoy headphone amp would probably make the exact same improvement as completely bypassing the iMac's DAC.
> 
> The DACs in Macs sound just as good as standalone DACs. The specs for them extend beyond the range of human hearing. No need to replace a Mac's DAC.


 
   
  So the builtin in DAC in Mac sounds as good as the $1000 Dac1 ?


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## bigshot

To human ears, yes. All of the improvements would be well beyond the range of human perception.

Here are the specifications for the DAC I'm pretty sure is in the iPod 5G...

http://www.wolfsonmicro.com/products/codecs/WM8758/

Note the signal to noise specs, The only way that a human would be able to hear that noise would be to turn the volume up to a level that hearing damage would certainly result. And this is in an inexpensive portable player.

Mac has always used top quality parts. Every single Mac product I've ever owned (and I have had dozens) has exactly the same sound... audibly perfect.

You can get better specs, but you can't hear them.


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## TMRaven

My old G5 iMac definitely doesn't sound like my current gen Apple products.  Its onboard audio was horrible-- complete with of bass rolloff and noise.  
   
  The 118-119db sensitivity IEMs aren't fair arguments I think.  Even lots of high dollar 'audiophile' amplifiers suffer with a noise floor with said sensitive IEMs.  With every ordinary product I ran through the 2009 iMac and 2010 iPod Touch, there was no noise, and the sound was well balanced and clean-- even up to 106db Denon D2000.


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## bigshot

I produced commercial CDs on a G5. They still sound great.


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## TMRaven

They sound like ass compared to modern macs.


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## bigshot

It's interesting how this thread has mutated from all Macs have inferior sound to just old Macs have inferior sound.

My first Mac with audio in and out was an 8500 AV. I captured both video and sound with it and it sounded just like a CD. I can't remember what the headphone out was like, because I only used that to monitor, but I did thorough testing of the captures comparing the source to the capture (as I do on every machine I get) and it was as clean as a whistle. I still use a G4 and G5 and those require a capture box, but the sound there is perfect too.


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## jaddie

Quote: 





tmraven said:


> They sound like ass compared to modern macs.


 
  Unusual descriptive. Assuming we might guess what a modern mac sounds like, what does the other...oh, never mind.


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## TMRaven

Everything else might have been fine audio wise, but the headphone out of my G5 iMac was-- to use a massive understatement-- less than ideal.


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## bigshot

A headphone amp would have probably fixed that problem. The soundcards in Macs are fine. It's just that different headphones react to headphone outputs differently.


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## d marc0

bigshot said:


> A headphone amp would have probably fixed that problem.* The soundcards in Macs are fine. It's just that different headphones react to headphone outputs differently.*


 

I can't believe some people not getting it when you've repeated this statement so many times...


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## bigshot

Maybe they're hard of hearing.


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## rigodeni

I have a latest gen 2013 iMac, and a high end PC with a Create X-FI Titanium Fatal1ty Pro Sound Card ($120). For my testing I used my Sennheiser HD 600's direct connected, no amp. I used Winamp on the PC and iTunes on the Mac, with the same sources, mostly MP3 at 320 kbps. I never use EQ, so this was off in all tests.
   
*Both the Mac and X-FI have plenty to drive the 600's to dangerous levels, with no audible hum *(SNR is equally good on both). I could not bear going beyond 70% volume on either one. But *they did not sound the same to me at all.* *The Mac **was noticeably more bass heavy, and lacked the sound stage and separation I heard on** the X-FI.* The mid's on the X-FI came through more, with a sparkle in the treble that the Mac was missing. In addition to this, although there was less bass quantity on the X-FI, I felt it was more composed and resulted in more definition. This became clear on songs with percussion instruments, you hear more detail with each stroke. Although I had to really listen analytically with each side by side to hear differences, they were clear.
   
  I would like to say *the iMac's DAC is substantially better than my PC's on-board. *However, most audiophiles agree that in general, *a DAC affects audible differences more so than an amp.* I found this to be true with my experience connecting my Fiio E11 and Bravo V2 amps through both the iMac and PC. *The differences I hear with amplification are much more subtle than the differences I hear between the iMac and X-FI DAC**s**. *Therefore, regardless whether you have a PC or a Mac,* I still suggest upgrading your DAC before getting amplification.*
   
*I must disagree with bigshot completely that you cannot hear the difference between an iMac's DAC and **a dedicated external one**.* I would venture to say bigshot probably doesn't own any high end DAC's himself. Just like with headphones, published specifications do not indicate very much about how a DAC will sound. There are several electrical design factors and materials that go into the execution of a quality DAC. There are numerous reviews of DAC's by Mac owners, like the Schiit Modi ($99). I have yet to read one that did not hear significant improvements. Note that some reviews have amps, but testing was done with the same amp on both the iMac and Modi. And this is just one example of a good sub $100 DAC.


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## stv014

Did you verify that:
  1. it is really the DAC that is making the difference (just because two amplifiers can both output loud sound, it does not mean that one cannot possibly clip or have much higher output impedance)
  2. you compare the devices at accurately matched (read: measured to be equal) levels
  3. all DSP (EQ, virtual surround, etc.) is disabled and you are comparing bit perfect streams
  4. sound cards are used with optimal mixer settings
  And, of course, since it is the Sound Science forum, it is reasonable to ask to test double blind as well, if possible.
   
  The large majority of casual DAC (and other) comparisons are sighted, not level matched, and the listener is expecting an improvement from the new gadget that has just been purchased. It is no wonder a difference is heard under such conditions.


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## bigshot

Do what stv014 suggests and the differences will likely disappear. Mac frequency response measures ruler flat. I'm not familiar with your PC soundcard, but I would hope it does too. They should sound the same if the frequencies they produce are the same.


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## rigodeni

Quote: 





stv014 said:


> Did you verify that:
> 1. it is really the DAC that is making the difference (just because two amplifiers can both output loud sound, it does not mean that one cannot possibly clip or have much higher output impedance)
> 2. you compare the devices at accurately matched (read: measured to be equal) levels
> 3. all DSP (EQ, virtual surround, etc.) is disabled and you are comparing bit perfect streams
> ...


 
   
  My test environment, or reviews of external DAC’s by actual Mac owners, may not satisfy you. That is fine, because *regardless of the environment, the findings will still be mine, not yours.* So if you really want to be sure, because it sounds like you do, *you should get your own external DAC and test it yourself under conditions that satisfy you*. I did just that, and to me it was obvious. If you’re willing and able, I would love to hear your experience with your own test environment.


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## stv014

Quote: 





rigodeni said:


> *you should get your own external DAC and test it yourself under conditions that satisfy you*.


 
   
  Why would I waste money on a device I do not need, for the sole purpose of proving a point that will then be ignored anyway ? With proper testing, chances are that I would not hear any difference compared to my existing equipment (that performs plenty well enough according to any tests I could do), which the audiophile crowd - who themselves usually avoid any kind of controlled listening tests - would just blame on "not having revealing enough gear" or defective hearing. It would not achieve anything useful.
   
  Quote:


rigodeni said:


> I did just that, and to me it was obvious.


 
   
  That is fine, but if you did not make it sure that your comparison is made in a fair way and with eliminating common problems that affect listening tests, then your experience is of purely anecdotal value, and should not be stated as a fact. You may think you heard a major difference, but it could very well have been imaginary, or the result of unmatched levels or incorrect setup/usage.


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## bigshot

I did a level matched A/B switchable comparison of a $900 SACD player, an iPod classic with an AIFF file through line out and a $40 Price Club Coby DVD player. It wasn't blind, but even so, once the levels had been matched, they all sounded exactly the same. I've done tests between my Mac Mini and my iPod and SACD player too. Same results.

Level matching and direct A/B switching are the most important parts of a controlled test. Very slight differences in volume and delay between samples can totally throw off a comparison.

My whole system is driven off a Mac Mini running AAC 256 VBR in iTunes. I guarantee you that it would blow your socks off. If you are evern LA, look me up.


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## One and a half

Quote: 





bigshot said:


> Optical cable or HDMI are best.


 
  Why would you choose the two highest jitter output connectors? In comparison, the analog out is far better, best is to use USB or FW if you have the right DAC.


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## Currawong

Quote: 





currawong said:


> I'm not sure how they derive the S/N ratio of a digital output, as that is totally different to the S/N ratio of an analog output.
> 
> Anyhow, here is a quick measurement of the headphone output of my MacBook Pro versus the the analogue loopback of the ULN-2 which I used for the measurement. These shouldn't be taken as professional measurements, just as a comparison. The measurements were done at around -6dB. I think a 20-40 dB difference in the amount of distortion at the levels shown is significant enough.
> 
> ...


 
   
  Allow me to quote my own post from a while back _showing_ that the noise from the output of my MacBook Pro is high.


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## rigodeni

Because I like to work in OSX more, I will be upgrading to the JDS Labs ODAC next month. I will compare it with my X-FI and the iMac's on-board. I have no A/B switch or fancy measurement equipment, but I will try to get my wife to assist me with a blind test. I have heard the ODAC fairs very well in blind tests. I would like to know that I can't hear a difference because this would save me money. But I am confident I can.


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## xnor

Quote: 





one and a half said:


> Why would you choose the two highest jitter output connectors? In comparison, the analog out is far better, best is to use USB or FW if you have the right DAC.


 
  Jitter problems with HDMI have been fixed years ago. S/PDIF is not the best for jitter, but what amounts are we talking about? Certainly not in the nanoseconds range. USB: not every receiver has USB inputs.


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## bigshot

Quote: 





rigodeni said:


> Because I like to work in OSX more, I will be upgrading to the JDS Labs ODAC next month. I will compare it with my X-FI and the iMac's on-board. I have no A/B switch or fancy measurement equipment, but I will try to get my wife to assist me with a blind test. I have heard the ODAC fairs very well in blind tests. I would like to know that I can't hear a difference because this would save me money. But I am confident I can.


 
   
  All you really need is an extra preamp to balance the line levels with.


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## stv014

Quote: 





one and a half said:


> Why would you choose the two highest jitter output connectors? In comparison, the analog out is far better, best is to use USB or FW if you have the right DAC.


 
   
  Optical S/PDIF may have higher (but with a competent implementation still nowhere near audible under realistic music listening conditions) jitter, but it prevents ground loops, which are a common real problem with computer based audio systems.


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## rigodeni

Quote: 





bigshot said:


> All you really need is an extra preamp to balance the line levels with.


 
  Neither my E11 or my Bravo V2 have a pre-out


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## jaddie

Quote: 





rigodeni said:


> Neither my E11 or my Bravo V2 have a pre-out


 
  No, but that's not the problem anyway.  When you're comparing DACs, one issue is the internal gain of the DAC.  If took a tone at 0dBFS and ran the data to two different DACs, you probably will get different output levels from them which makes comparison impossible.  If at least one DAC had a means of output level control so you could make sure both DACs reproduce identical levels, then you can compare them properly.  bigshot suggested a preamp between one of the DACs to assist in level matching (balancing). Once you have both DACs level matched, you can connect them to your favorite amp.


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## stv014

In the case of DACs, it is also important to synchronize them as accurately as possible.


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## AudioBro

I am getting an imac soon.  DO i need a dac/amp to power some good headphones like the lcd-2?


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## bigshot

Probably not. My new iMac has a pretty powerful output.


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## xnor

Anyone have specs on that output? Who knows what output impedance it has and max output voltage it can do?


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## jaddie

http://support.apple.com/kb/TA26045?viewlocale=en_US&locale=en_US
   
  Don't think that's for the current model though.
   
  Then there's this - late 2011 (scroll down a bit):
http://support.apple.com/kb/HT4619
   
  And late 2012 (most recent except the new thin ones, which don't have their audio out specs published yet)
http://support.apple.com/kb/HT5522#1


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## xnor

Quote: 





jaddie said:


> And late 2012 (most recent except the new thin ones, which don't have their audio out specs published yet)
> http://support.apple.com/kb/HT5522#1


 
   If its similar to that it won't go very loud especially with stuff like classical music.


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## Venasa

I am aware this is a bit of an ancient thread but I wanted to ask the specific people here. Is there really no point in an external DAC then? If that's the case why is there such a range of both external and internal DAC's to choose from? Furthermore do you think there is much benefit in a desktop amplifier at all? Take the Schiit Bifrost for example? 
  
 I'm just trying to get a better bearing on what is being said here.


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## Roly1650

venasa said:


> I am aware this is a bit of an ancient thread but I wanted to ask the specific people here. Is there really no point in an external DAC then? If that's the case why is there such a range of both external and internal DAC's to choose from? Furthermore do you think there is much benefit in a desktop amplifier at all? Take the Schiit Bifrost for example?
> 
> I'm just trying to get a better bearing on what is being said here.


 

 I think the general agreement is that Apple products are audibly transparent devices and an external dac brings nothing to the party.
 The built in amp in the Mac will probably work OK for 90% of the phones on the market. Try the phones with the Mac first, the cheapest way. You may need a desktop amp, if you can't drive the phones loud enough with the Mac, but it wont be adding anything to the sound quality if you do.


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## ph0rk

venasa said:


> I am aware this is a bit of an ancient thread but I wanted to ask the specific people here. Is there really no point in an external DAC then? If that's the case why is there such a range of both external and internal DAC's to choose from? Furthermore do you think there is much benefit in a desktop amplifier at all? Take the Schiit Bifrost for example?
> 
> I'm just trying to get a better bearing on what is being said here.


 
  
 They may be useful in some cases - in the pc world, for example, there are often noisy internals, and getting the DAC out of they main case can help with that sort of noise.
  
 But the main reason is that people like to buy things, and DACs have exploded in the last 5-6 years.
  
 Desktop amplifiers can help with impedance issues (say, if you have a K7xx headphone, you'd want as low an output impedance as possible), or with low sensitivity headphones (that is - not loud enough for you at max volume) but you don't need to spend very much to get something that will do the job: an o2 is more than you'd need in almost all cases save for some very "special" headphones that need ridiculous power (like the K1000). 
  
 And, well, like I said - people like to buy things. And audio makers are clever at packaging and marketing a "look" or image of their products. Look at all the listening station porn and you'll see it. Think of it as desk jewelry.


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## shigzeo

currawong said:


> I'm not sure how they derive the S/N ratio of a digital output, as that is totally different to the S/N ratio of an analog output.
> 
> Anyhow, here is a quick measurement of the headphone output of my MacBook Pro versus the the analogue loopback of the ULN-2 which I used for the measurement. These shouldn't be taken as professional measurements, just as a comparison. The measurements were done at around -6dB. I think a 20-40 dB difference in the amount of distortion at the levels shown is significant enough.
> 
> ...


 

 I'm with you re: noise. It's better than one or two dedicated amps I've used, but, through sensitive earphones is worse than 95% of what I've tried. That said, it measures extremely well. I've put up basic RMAA measurements of it at ohm. If it didn't hiss, I'd be confident to use just it as it has both power enough (not perfect) and control.


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## watchnerd

When I'm not using an external interface / DAC I use the jack on the Mac Mini to power a Mjolnir 2.
  
 Works great.


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## tonykaz

Mistah watchnerd,
  
 For god's sake man, your missing the dog fight of the century, hap'n on Stereophile's Audioquest expose : about the validity of $1,000 HDMI cable. 
  
 Audioquest's Lowe, Stereophile's JA, Dr.dalethorn, Spacehound and plenty of others are in a Brawl, phew, pseudo science and non-sense aplenty.   
  
 They need a Ghost Buster.
  
 Tony in Michigan ( New Hampshire )


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## watchnerd

tonykaz said:


> Mistah watchnerd,
> 
> For god's sake man, your missing the dog fight of the century, hap'n on Stereophile's Audioquest expose : about the validity of $1,000 HDMI cable.
> 
> ...


 
  
 link?


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## nick_charles

watchnerd said:


> link?


 
  
Link to audioquest massacre


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## watchnerd

nick_charles said:


> Link to audioquest massacre


 
  
 Thanks, although I'm not going to dissect the responses here as I think we already have a thread for this topic.


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## shigzeo

I should have said sorry for resurrecting the thread.


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## watchnerd

shigzeo said:


> I should have said sorry for resurrecting the thread.


 
  
 why?


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## shigzeo

Because it was like 2,5 years old. I'm sorry for that. But yeah, I'm pretty impressed with the iMac's output. 1,4 VRMS is decent and it certainly holds load well. If it didn't hiss with sensitive earphones, it would be worthwhile on its own.


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## watchnerd

shigzeo said:


> Because it was like 2,5 years old. I'm sorry for that. But yeah, I'm pretty impressed with the iMac's output. 1,4 VRMS is decent and it certainly holds load well. If it didn't hiss with sensitive earphones, it would be worthwhile on its own.


 
  
 right now I have mine running DAC-less into a Mjolnir 2 -- the amp costs  more than the computer LOL.


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## Faizan Khan

I am Listener not a professional Guide. I am not sure but People say I have a good ears, I think I have my own taste in listening.
  
 I am 50 years old Live in Pakistan, and listening music since I was 10. Gone through through various hi fi from mono cassette player to high end equipments.
  
 At present I have B&W Nautilus 801 speakers, Anthem and Conrad Johnson pre amp, Mcintosh and Anthem Power, A ARCAM cd player Oppo Blu Ray Player,  iMac (Retina 5K, 27-inch) , All this equipment for Music and Movies. May be a good $50 to $60 thousand  insvement. I am not a rich man and took me 30 years to reach there. 
  
 I experienced a lot equipment during this period few of them were including speakers and other equipment i.e. Wilson Audio, Akai, JBL, klipsch, Sansui, NAD, Nakamichi, Luxman, Pioneer, Bel Canto, Devialet, Dynaudio, Canton, Sony, Focal, JVC, Denon, Esoteric, Paradigm and many more I can even remember.
  
 I also invested some time in room acoustic to get better results in a domestic and real living situation with family. not in a isolated studio type environment.
  
 Listens variety of music but at present in to Electronic, like Ace Dana just one example out of hundreds, Artist and types of music. I am a Bass Head. To me High notes can be achieved relatively easily the secret is in midrange and Bass, The more nice Bass the lower the DBs the cost of speakers goes higher.
  
 At the moment with my  iMac (Retina 5K, 27-inch) I was interested in buying a DAC for my headphones (Beats Pro, Beats Mixr and V-MODA Crossfade M-100 ) 
  
 I was doing my research for DACs for last 20 Day. I have made my opinion what is largely said on net. I have not listen any of them yet and listening choice is very subjective, They Cost from $35 to $999.
  
 My final selection is OPPO HA2 $300, Mojo $600, and Micca OriGen+ High Resolution USB DAC and Preamplifier $100.
  
 All Dragonfly dac type things are out they are cheap but u will spend $100 more on cables, external batteries, converters etc, to make them workable with other gadgets, In my case I use apple Stuff my wife is an Android person my children or mix (Iphone, samsung tab/phones, Apple ipad, Nanoo, niini bla bla bla. and top of that we have also have a Hifi, wifi, Media Player etc system.
  
 And final decision is I DO NOT NEED A DAC with mac, I can not listen more louder what Mac offers on high volume all above mentioned devices can damage your ears. And a thing which nobody talks is, That quality depends on you actual music recording. For example I like ENIGMA I almost have all of their albums (original Cds), All albums are recorded nicely but 7 Lifes is a very bad recording on original Cd. What I am trying to explain if my original source file is of a good quality Mac does not  disappoint me with my set up Highend end and even headphones.
  
 Plus You can always use Equalizer to make it suitable for your years. 
  
 Hope It will help, apologize me for my bad english since I am not native english speaking person


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## Wisenlucky

Faizan Khan said:


> ...And final decision is I DO NOT NEED A DAC with mac, I can not listen more louder what Mac offers on high volume all above mentioned devices can damage your ears...



I second that! I own iMac (Retina 5K, 27-inch). I've bought myself Sennheiser 6xx + O2 SDAC/AMP. https://drop.com/buy/massdrop-o2-sdac-dac-amp.

There was absolutely no difference in sound quality listening directly from iMac or O2. Even when I tried to invent any difference in my brain.  

Yes O2 probably might drive my 6xx to a higher volume, but unless you want to damage your ears you don't want to do that. 

I did feel that I might need extra few db of volume when listening from MBP 13 2019 though. 

In that case O2 came handy. But iMac is great. I still have this itchy feeling that a tube amp would make an improvement in sound. But at this point I've decided to just sell the whole set, add a few hundred and get next level cans to listen directly from the iMac.


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