# So How Much DOES a DAC/Amp Improve iPhone Output - Some Experiments



## ruthieandjohn (Jul 8, 2017)

Over my years on head-fi, I have had a fascination with high-quality portable audio from an iPhone or iPod, and over the years I have accumulated many portable DAC/amps:

*  Chord Hugo (approximate price new $1,500)
*  CEntrance HiFiM8 ($700)
*  CEntrance HiFi Skyn ($400)
*  Sony PHA-1 ($244)
*  Sony PHA-3 ($998)
*  V-MODA VAMP VERZA ($400)
*  Beyerdynamic A 200p ($150).

Since I have all of these at hand together right now, it seemed useful to compare how each alters the sound of the iPhone by comparing sound from the iPhone directly vs. sound from the iPhone and through one or more of these DAC/amps, as well as comparing one DAC/amp to another with both being driven by the iPhone.

I have also developed a set of 10 comparative listening tests that I have used to compare over 50 different headphones, in over 50 three-way comparisons.  These tests are described *here*.  My goal was to apply these tests, or something similar, to rank order the improvement that each of these DAC/amps made over direct iPhone output.

I wanted to calibrate my ear to what changes to expect from a really good DAC/amp, so I began my comparison by picking what many acknowledge to be the best of the DAC/amps above, the Chord Hugo (certainly the most expensive as well), to compare with the case of no DAC/amp (i.e., direct from iPhone).  I puzzled over which headphones to use for the comparison and started with the near-top-of-the-line Grado PS1000e.  Grados are known as "fun" headphones, rather than accurate, and the PS1000e is their most resolving.  The Grados are relatively easy to drive from an iPhone, having a sensitivity of SPL 99.8 dB at 1 mW (and a 32 ohm impedance).

My iPhone is a 5S, and the recording I started with was the first of the four I have used in the comprehensive tests above, the song "You're Going To Miss Me When I'm Gone," from the album _One Foot In The Ether_ by the Band of Heathens. The album was played as a CD lossless rip at 44.1 Ksamples/sec, rather than the lossy AAC format that is standard with Apple iTunes. I compared with and without the Chord Hugo.

Well....

There were no night-and-day differences!  I had to switch between the two cases (w vs. w/o Hugo) many times before I began to discern that the guitar that appears in the first few seconds seemed a bit farther away with the Hugo than without.  I eventually spun that into a perception that the soundstage was a bit larger and more enveloping with the Hugo than without.

A bit more listening caused me to start to perceive that each instrument in the Hugo version might be just a bit more separated in space from other instruments than in the iPhone output directly, and eventually I developed the mental image of the band members being positioned inside the surface a balloon (where I, as listener, was positioned in the interior of the balloon, say a bit further from the band than center).  For the Hugo, the distance to the instruments on the surface of the balloon was larger than without the Hugo.  Hence, the better the DAC, the larger the balloon around me that had the instruments pasted to its inner wall.

I did not hear any differences in tonality, either in the bass drum, in the high frequency snare and cymbals, or in the guitar or piano (and I listened hard for them!)

It is hard to characterize just how great this difference was, but I can create sort of a hierarchical checklist:

Do I think that I could reliability tell in blind randomly-selected tests of the two cases (with Hugo vs. straight from iPhone w/o Hugo) that the current iteration was the same as or different than the previous one?  Yes, with perhaps 85% certainty;
Do I think that I could tell which was the Hugo and which was not, again in consecutive blind random tests?  Yes, but with only about 67% certainty... I would expect to be wrong maybe 1/3 of the time!
Do I think I could after leaving the setup and coming back after an hour or more, tell at first listen whether I was hearing with the Hugo or direct from the iPhone without the Hugo?  No... no better than 50% (i.e. same as the random choice of flipping a coin).
(Note that these are not actual blind tests... they are my prediction of how I would do on a blind test).

So...

What am I to do to accentuate the differences?  What sort of sounds better exploit the advantage offered by the best DAC/amp available to me than the small rock ensemble of lead guitar, rhythm guitar, bass, vocals (2), drum set, and piano?  Or should I try different headphones than the PS1000e?

So far I have tried the following, but not found any combination that makes a bigger audible difference than what I had seen so far:

Tried the Grado HP1000 HP1 headphone (the original and most linear of the Grados, from 1990);
Tried the Grado RS2e headphone (brighter, smaller soundstage)
Tried the Grado GS1000i headphone (I rank this as my best Grado, with the RS2e as second) - the GS series is known for its huge sound stage, and the GS1000i preserves a lot of high frequency content that perhaps would accentuate the effect of the Hugo;
Tried the Sennheiser HD800 (notoriously hard to drive and hardly ever used alone with the iPhone, though the Chord Hugo is said to be a good source for these headphones -- the prediction was that the HD800 would sound horrible from the iPhone and great from the Hugo, but that was NOT the case!);
Tried Saint Saens Organ Symphony as a more complicated piece than a rock group;
Tried Beethoven's Third Symphony as a full orchestral piece rather than an orchestra backing an organ.
In all cases, my listening is repetitive over just a few seconds of the same passage of music, for the rock group concentrating through multiple listens on the boominess / pitch of the bass drum, the clarity and position of the guitar, the angle subtended by the whole ensemble, the transparency of the overall sound (i.e. not muffled as in from around a corner), the impact of snare drum and the sizzle of the cymbal.

I started a comparison with the least expensive DAC/amp on the list, the Beyerdynamic A 200 p, to find that it indeed lay between the bare iPhone and the Hugo, and closer to the iPhone, in its ability to place the instruments inside a balloon (i.e., the balloon was smaller with the Beyerdynamic).

I will continue to listen to what should be the two extremes of this range of DAC/amps, in hopes of finding more clues to focus on for comparison, so that I might start ranking the effects of the various DAC/amps listed at the beginning of this.  I will also listen to some sister models of Grado headphones, as I suspect one way of characterizing this small degree of difference would be something like "It is similar in difference to the difference one hears between the Grado RS1i vs. the RS2i") or some such.

All advice on comparison methods, what to listen for, sample music, or anything else is welcome.  If I succeed in perceiving reliable differences, I will post the results, as I have the unique opportunity of comparing 8 portable DAC/amps (including direct from iPhone).


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## ruthieandjohn (Jul 16, 2017)

Continuing my saga...

Perhaps the music that I used, so familiar to me, is not the best to discriminate the properties of various DAC/amps.  Hence, I began reading reviews of the Chord Hugo, hoping to find musical pieces that reviewers have used to compare the Hugo to anything.  So far..

Michael Jackson "Don't Stop Till You Get Enough" - no significant difference with or without Hugo between iPhone and headphone;
Massive Attack "Unfinished Sympathy" - bass is a bit tighter and just a bit stronger with the Hugo in the path;
Justin Timberlake "Blue Ocean" - bass, and indeed all, instruments are just a bit tighter, as if fastened by short springy bars with the Hugo and longer, floppier bars without;
Stevie Wonder "Higher Ground" - a bit larger balloon (see above), i.e., instruments are spread out just a bit more with the Hugo;
Infected Mushroom "Noon" - perhaps the largest difference of with vs. without Hugo in the path - tighter bass, more space between instruments with the Hugo;
Asian Paper Circus "Silent Strike" - Hugo provides an increase in the balloon size, i.e., larger soundstage.


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## ruthieandjohn

Next in my quest, I went to high-resolution music, using the Onkyo HF app on my iPhone to play "Limehouse Blues" from _Jazz At The Pawnshop_  as 96 ksamples/sec WAV file.

Again I compared out of the Chord Hugo with straight out of my iPhone... no perceptible difference.

Following advice from @Music Alchemist , I added a headphone switch and a second source.  At this point, I had my iPhone 5S and my iPod Touch 6Gen playing the same hi-res file, with one path going via digital Lightening connector and CCK adapter from the iPod into the Hugo and then into the switch, and the other path going directly from the iPhone into the switch.  Turning the knob on the switch allowed me to instantly change listening from one to the other, and I aligned the start times so that both were in the same place in the music.

Ideally, even though one source is an iPod and one is an iPhone, both are being read as digital streams that come through the same player from the same digital source file.

Listening... STILL no difference!

I tried CD-quality music (44.1 Ksamples/sec as before)... still no difference.

I tried jazz group, rock group, piano concerto with orchestra... still no difference.

I got my wife Ruthie, who can hear differences that I miss, to listen to both, switching from one to the other when desired.  Still no difference.

I then replaced the Chord Hugo with the much less expensive Beyerdynamic A 200 p belt-mounted DAC, amp, and iPhone control.  Still no difference.

I tried using some of the music above in streaming mode, but due to Apple Music constraints, I could only have one device on at a time, so I could not instantly "flicker" between one and the other path.

I suspect a reasonable next step would be to purchase some of the above music, where yesterday a miniscule difference was heard, and use the switch arrangement to quickly flicker between one and the other.

We'll see...


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## abirdie4me

ruthieandjohn said:


> Next in my quest, I went to high-resolution music, using the Onkyo HF app on my iPhone to play "Limehouse Blues" from _Jazz At The Pawnshop_  as 96 ksamples/sec WAV file.
> 
> Again I compared out of the Chord Hugo with straight out of my iPhone... no perceptible difference.
> 
> ...



Thanks for all your efforts! My experience with the Mojo vs. iPhone/iPad direct has (anecdotally) produced the same results...virtually no difference in SQ. The good news is that I don’t believe this to be a failing of the Mojo, but more of the iDevices having surprisingly good sound. Look forward to seeing more of your results.


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## ruthieandjohn (Jul 10, 2017)

I agree that iPhone quality has increase significantly with the iphone 5S, over earlier iPhone models.  In fact there is a thread on this improvement here in head-fi.


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## Jazmanaut

In my ecperiences, its not so much about soundquality, but you can have a bit more effortless playback.
Especially in bass. Sometimes when i listen very huge orchestral piece with big crescendo, it can get distorted and limits dynamics. There is just not enough juice.
And offcourse if your headphones are hard to drive, differences are more in frame.


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## abirdie4me

I am surprisingly finding the same thing to be true with my Google Pixel, it sounds the same as my Mojo.


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## jkjk123

Thanks for doing this test! It does seem to confirm several people's opinions that there is very little discernible differences between good DAC/AMP combos when volume has been equalized between them.


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## ruthieandjohn (Jul 16, 2017)

One thought is that the effects of a better DAC are long term,  e.g., a better DAC allows a greater interval before listening fatigue sets in than with a poorer DAC.  That would mean that listening to few-second snippets in a "flicker" mode of switching rapidly between them is not the best way to compare DACs.

Instead, one should listen to one DAC for long period, long enough to become the baseline expectation of that configuration. For example, one could listen to an unfamiliar piece of music, over and over, until it becomes familiar.  Then, one switches to the other DAC and listens, looking for new insight into the recording ("hey, I never heard that triangle before!") as well as comparing the overall feel (e.g., spaciousness).

Then listen to another new piece repeatedly with the second DAC configuration, repeating until familiar, then switching to the first DAC and repeating the process.

I have been trying that in the iPhone with and with Chord Hugo in the path and might hear small differences that I had not before.  However, it does not feel definitive in the least!


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## Bansaku

abirdie4me said:


> The good news is that I don’t believe this to be a failing of the Mojo, but more of the iDevices having surprisingly good sound.



100% correct! People tend to scoff at the notion that an iDevice audio is class leading. I have seen numerous measurements of various iDevices and in all honesty it doesn't get much better in terms of portable sound; Apple is no dummy when it comes to audio. While there has been notable audible changes between versions of the iDevices, from my experience it basically can be accounted for with a click up or down on the volume (different amp used), and not so much in regards to real sonic improvements. The way I like to think of it is ' digital is as digital does '.

@ruthieandjohn 
All an external amp will do is allow you to use higher impedance headphones, and all an external DAC does is allows for higher than 24/48 resolution (AIFF and ALAC) iDevices max out at. I won't deny that some amps/DACs do sound better than others, though it's not because one is "better", it's that one is simply sub-par. It's like how do you improve upon 100% pure water? You can't, but definitely there is water out there that is not as clean.

Moving to a desktop/home setup is a whole different storey...


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## Deftone

Confident in hearing improvement with mojo ( which I've had since launch day ) I have decided to do a test also. Using a cheap pair of Sony MdrEX650, running straight from my Moto G5 smartphone the treble stands out instantly it's wild and splashy, I didn't even know they could sound this way as I've never used them with only my phone, flicking back to mojo the sound is noticeably warmer and refined smoother treble. Then flicking back to G5 bass is thinner not as deep the harsh treble is starting to grate on my ears as I'm not used to hearing it like this. 

I'm surprised from this test I wasn't expecting it to be such a difference with £40 iems.


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## ruthieandjohn

I do suspect that other phones might not sound as good as an iPhone, and hence might be more enhanced when their DAC and amp are supplanted by the Hugo (or in this case. Mojo).  Maybe that is what is going on here.  Be fun to try with an iPhone 5S.


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## Deftone

Well maybe it's time to sell your Hugo?

I didn't know iPhones were as good as SOTA DACs, interesting.


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## ruthieandjohn

@Deftone, what song(s) were you using on your Moto G5 smartphone vs your Mojo to notice those differences you'd mentioned above.  I'd love to try them!  Thanks!


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## Roen

abirdie4me said:


> I am surprisingly finding the same thing to be true with my Google Pixel, it sounds the same as my Mojo.


Pixel HP out channel imbalance is supposed to be horrible.


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## abirdie4me

Roen said:


> Pixel HP out channel imbalance is supposed to be horrible.



Not that I can tell, but then again I'm beginning to believe I'm half deaf as I can rarely hear the things that others describe on these forums. The only obvious differences I'm hearing is with headphones, the 3 or 4 amps and dacs I've had so far have very little impact on SQ.


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## Currawong

I often find it harder to A/B snippets of songs, unless I'm listening for specific things, like the detail of note decay in a particular track, and that with guitars, pianos or violin. How I feel listening to a whole track out of a DAP versus one of the Chord DACs is different, however. But the difference is more noticeable if I am using a better USB source. The original Hugo is vastly improved if you even put a Schiit Wyrd between it and your phone in my opinion.


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## Deftone

ruthieandjohn said:


> @Deftone, what song(s) were you using on your Moto G5 smartphone vs your Mojo to notice those differences you'd mentioned above.  I'd love to try them!  Thanks!



All my music is CD rips WAV 16/44

Machine Head - Imperium

Trivium - until the world goes cold

Horrendous - the vermilion


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## TWerk (Sep 24, 2021)

abirdie4me said:


> Thanks for all your efforts! My experience with the Mojo vs. iPhone/iPad direct has (anecdotally) produced the same results...virtually no difference in SQ. The good news is that I don’t believe this to be a failing of the Mojo, but more of the iDevices having surprisingly good sound. Look forward to seeing more of your results.




I own apple devices (macbook air, iphone). Most of everything I do is on my little Macbook air. I find the sound output to be excellent and I've tried many little portable DAC/AMP combo units and find very little difference, if any at all. I actually often find the sound becomes WORSE than running direct into the apple device's headphone output. I find the apple devices to offer a nice smooth and non-fatiguing sound. Like, for example, when I tried an ODAC and O2, the treble became sharp, harsh, with a sheen on it that is not present on my headphone output on the apple device. I recently sold a little Fiio E10k which also did not really improve much of anything for me. I thought the Audeze Deckard was a good amp for my HE-500, it surely made an obvious improvement vs directly into the macbook, however, after getting rid of my HE-500, I didn't feel the improvement was strong enough when I could stick my other headphones right into my computer and get quite similar sound. I was mainly keeping the Deckard for the HE-500 and it became apparent that was costing me near $800 for the two, which being a sort of minimalist person, didn't seem worth it to keep the pairing.

Out of all the DAC/AMP devices I've had though, I liked the Deckard best but again, not enough to keep it. The difference with a dedicated amp/DAC system IMO is overall pretty minimal. Even with something like a HUGO vs an iphone, you are finding it very minimal and that is a very expensive device we are talking about... A great recording simply sounds great on a macbook, as long as your not using a super power hungry headphone like maybe HE-500. Even my Beyer T1 sounds excellent into my air.

I am very glad this honest thread exists, you honestly call it like it is. Frankly, I am very skeptical now of improvements with these devices (especially the portable ones). And there might even be some improvement but is it worth the price? Like if the Deckard was 100, I probably wouldn't have sold it but at 400, it is much less desirable. I'd rather budget that money towards something else.

They often design them to look very pretty and expensive though, which might explain some things...


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## Currawong

I agree -- I think the main factor has been how much phones have improved in sound quality. The inexpensive FiiO gear was a big deal when phones had lousy audio.  Where a good DAP or the like makes a big difference is with $1000+ IEMs in my experience. When non-audiophile friends ask about what is good to buy nowadays to use with their phone, I often suggest Bluetooth headphones, which have become good, or sometimes better than many of the wired models.


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## TWerk (Jul 16, 2017)

This review of the Iphone 5 quality mirrors what you have found as well in your own listening sessions.

Be sure to check out the conclusion section.

http://www.kenrockwell.com/apple/iphone-5/audio-quality.htm


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## NaiveSound

Note 5 or mojo is very similar... Kinda looking to get a dap that just has Tidal.... Mojo isn't what it's hyped to be


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## TWerk

So you also find your phone (note 5) to be quite similar to the chord. Good to know. Sadly the mojo costs as much as the whole phone itself! Crazy.


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## Deftone

NaiveSound said:


> Note 5 or mojo is very similar... Kinda looking to get a dap that just has Tidal.... Mojo isn't what it's hyped to be



Weren't you in love with the Zues and Mojo combo though ?


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## NaiveSound

Deftone said:


> Weren't you in love with the Zues and Mojo combo though ?




Yes I was. Absolutely living the Zeus! But the Mojo? Idk... It's a detail God... But so is Zeus, it can extract that out of most things.... The thing is that my note 5...is just about as good as mojo.... It's just not that impressive ( the Mojo).  I like it's colored balls the most...


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## jrflanne

I really like the sound and convenience of my iPhone 6. I bought an AK100ii, thinking it would be some great upgrade. Sounds good. And a total pain. I never listen to it but I listen to the iPhone all of the time. It is pretty impressive.


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## ruthieandjohn

I have the Beyerdynamic version of the AK10, which is the A200p.  It is a postage-stamp-size DAC with a huge disc for a multi-turn volume control.  It mounts in the belt with the iPhone in your pocket, and it transfers the transport controls (stop, skip, replay) to a place you can actually get to them without digging out your iPhone.


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## Slaphead

I have to say that my experience mirrors that of @ruthieandjohn in that adding an external DAC/Amp to a phone, well a relatively modern Apple device at least, doesn't really bring much to the table. However this is only to a point.

If you're using headphones that will give you a good to loud-ish listening level at around 60 to 70% volume level, or less, from the iToy's headphone jack (or lightning adapter) then I've found that adding an external DAC doesn't make much difference beyond slight tonal changes. For example my Mojo sounds just a touch warmer, and my DFR just a touch brighter than the iToy's output, which I consider to be pretty neutral overall. However these tonal changes are very small, and there isn't much, if anything, in the way of detail, layering, dynamics and soundstage improvements. I certainly couldn't tell the difference in a volume matched blind test.

If on the other hand you're using headphones that require an 80 to 90% volume level to be listenable, then my experience tells me that you really will reap the benefits of an external DAC/Amp. For instance take the Beyer DT1770 Pro at 250Ω. They can just be driven to listenable levels by an iToy because they are actually quite sensitive, but put a Mojo or DFR in the chain and suddenly there is a night and day difference in the presentation, with vastly improved dynamics, detail retrieval and layering. The iToy sounds positively flat, dull and anemic in comparison.

I personally think that the people who say they can't hear the difference between an external DAC and their phone are probably already using headphones that fit well within the power output envelope of their phone, and therefore they won't experience much in the way of an improvement, if at all.

Of course this does leave the question of whether it's just the Amp section of the DAC/Amp that's responsible for the improvement when using hard to drive headphones.


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## ruthieandjohn (Jul 26, 2017)

Good points, @Slaphead .  I was quite conscious of the fact that I was using headphones that are already easy for the iPhone to drive (Grados and HiFIMAN HE1000).  I did, desparate to hear a change, also try my Sennheiser HD800s either direct from iPhone or via the Hugo, but only briefly and not loudly (but still no significant change, but didn't explore much).


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## TWerk

Slaphead said:


> I have to say that my experience mirrors that of @ruthieandjohn in that adding an external DAC/Amp to a phone, well a relatively modern Apple device at least, doesn't really bring much to the table. However this is only to a point.
> 
> If you're using headphones that will give you a good to loud-ish listening level at around 60 to 70% volume level, or less, from the iToy's headphone jack (or lightning adapter) then I've found that adding an external DAC doesn't make much difference beyond slight tonal changes. For example my Mojo sounds just a touch warmer, and my DFR just a touch brighter than the iToy's output, which I consider to be pretty neutral overall. However these tonal changes are very small, and there isn't much, if anything, in the way of detail, layering, dynamics and soundstage improvements. I certainly couldn't tell the difference in a volume matched blind test.
> 
> ...




@Slaphead

I use my Beyer t1 right into my macbook and it sounds fantastic. As good as anything I've heard. 600 ohms. Plenty of volume on hand. Riddle me that one


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## Slaphead

TWerk said:


> @Slaphead
> 
> I use my Beyer t1 right into my macbook and it sounds fantastic. As good as anything I've heard. 600 ohms. Plenty of volume on hand. Riddle me that one



OK, when I say Apple device, I really mean iToy, at least within the context of my previous post.

The computers generally have far more powerful amplifiers in order to drive speakers - my aging 2011 iMac delivers 17 Watts per channel. That said I'm not sure how much of that power is available through the HP jack, but it could explain why you have no issues with your 600Ω T1s from your MacBook.

iToys on the other hand are limited to approx 1V RMS at the headphone Jack as far as I'm aware (0.5 V in Europe), and therefore likely lack the necessary voltage swing needed to drive high impedance headphones effectively - even sensitive high impedance HPs. The iPad may have a higher output however, though I'm not sure.

All of that aside, there's really no argument about the general audio quality from Apple gear.


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## Currawong

Slaphead said:


> OK, when I say Apple device, I really mean iToy, at least within the context of my previous post.
> 
> The computers generally have far more powerful amplifiers in order to drive speakers - my aging 2011 iMac delivers 17 Watts per channel. That said I'm not sure how much of that power is available through the HP jack, but it could explain why you have no issues with your 600Ω T1s from your MacBook.
> 
> ...



Where did you get that 17 Watts per channel figure? There is no way that is correct. The power consumption and heat would be astronomical.

I have an iPhone 6, and while it does quite well with IEMs, there are some, like the Campfire Vegas, which are clearly more resolving with better gear, like a Mojo, to the point I consider them a "don't buy" if you're going to just use them out of an iPhone.


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## Slaphead

Currawong said:


> *Where did you get that 17 Watts per channel figure? There is no way that is correct. The power consumption and heat would be astronomical.*
> 
> I have an iPhone 6, and while it does quite well with IEMs, there are some, like the Campfire Vegas, which are clearly more resolving with better gear, like a Mojo, to the point I consider them a "don't buy" if you're going to just use them out of an iPhone.



Here - https://support.apple.com/kb/sp623?locale=en_GB

The amps are class D, so are incredibly efficient (in excess of 90%) with virtually no heat dissipation at 17 watts.


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## Currawong

That's going to be for the speakers. 17W into headphones = blown drivers and eardrums.


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## ruthieandjohn

CLOSED.


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