# HRT DSP / iDSP



## Earbones

Thought I'd start a thread for these soon-to-be-released mighty mice from High Resolution Technologies.
  
 I'll be posting a review of the iDSP and a comparison with the Microstreamer (as well as a few other portable DAC/amp units) hopefully within the next few days. 
  
 Stay tuned!


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## Earbones

*High Resolution Technologies i-dSp* ​ The Mighty Mighty Mids Machine​  
  
​  
  
Right off the bat, let's get one thing straight... The i-dSp is not a microStreamer Lite. That was certainly my assumption, upon learning that Southern California's High Resolution Technologies would be releasing a $69 DAC/headphone amp with hopes of capturing a chunk of the burgeoning smartphone audio market. 
  
Speaking with HRT's Michael Hobson, my assumption was all but confirmed: 
  
(paraphrased) "We think it's great if audiophiles, guys who are a little more serious about it, enjoy the i-dSp. But we designed it for the guys with Beats, with Skullcandy... The masses. To bring a $69 device to market, we're not planning on selling a few of these within a small market. We plan on selling a ton within the large market of average consumers who stream Spotify, Tidal, or similar on their phone".  
  
Okay, I thought. So a microStreamer Lite. A little less sophisticated, maybe some boosted lows. A sound for the masses. What can one expect for $69?
  
A lot, as it turns out. 
  
No, the i-dSp is definitely not a microStreamer Lite. In fact, an argument could be made for the microStreamer being an i-dSp Lite... At least when used with an iOS device. The new kid is that good. Let's start with the basics.
  
  
  
​  ​  ​ The Form Factor​  
As you can see, the i-dSp is somewhat longer and thinner than the microStreamer. Sans cables, the two devices are essentially a wash when it comes to form factor... Different shapes, near-identical size.
  
However when paired with the cables necessary to attach them to an iOS device, the i-dSp clearly becomes the smaller and more manageable of the two:
  
​  ​  
The small size of the i-dSp (shown below with an iPod 5g) is not without it's hurdles however. While some may be fine with it hanging off the back of an iOS device like a dongle, others will want a more manageable package for use in pockets. Traditional rubber audio straps like those sold by FiiO are too large. I got it reasonably secure with a regular old rubber band, however. An even cleaner and more secure solution would be two thin strips of adhesive-backed velcro. 
  
  
  
​  ​  
  
The Build and Connectivity​  
The i-dSp is designed to be a simple plug-and-play device. No volume controls. No controls of any kind, as a matter of fact. A single LED adorns the sleek white body. "i-dSp" Is engraved beside that. One end of the device is open for an Apple Lightning to USB Camera Adaptor, and the other end has a single 3.5mm headphone jack. That's it. For the most part, the i-dSp is completely featureless. 
  
In keeping with this spartan approach, the i-dSp is designed to work only with iOS devices. The hollow end where the camera adaptor goes is essentially a recessed male USB type A jack, but the fit with the Apple adaptor is so tight, I doubt an aftermarket female USB type-A cable would fit, so a direct connection to a PC seems doubtful. It's worth mentioning that a quick Google search did unearth a female Lightning to micro USB cable... So I suppose if one were so inclined, they could rig the i-dSp > Apple camera adaptor > female Lightning to micro USB > micro USB to USB type-A > PC... But I have no idea if this would work. The microStreamer has a much less exotic USB Mini port, meaning connecting to a PC is a snap. 
  
The Specs​  
The i-dSp won't play your DSD files. Let's get that out of the way. It will handle lossless files up to 96 kHz and 24 bit. Going back to my conversation with Michael Hobson, the real thrust of the i-dSp's design was to create a simple device that would play lossless streaming beautifully. HRT believes the future for mobile audio is lossless streaming services such as Tidal or the rumored upcoming Apple hi-rez rebrand of the Beats subscription service. 
  
I tend to agree. DSD is great, but my collection is sparse. I remember a while back a better reviewer than I remarked that the DSD market looked like his grandmother's record collection... A few Norah Jones albums and bunch of classic Jazz recordings. Years later, that still rings pretty true to me. I won't wax on regarding which format is better... DSD is great. But there just isn't very much of it. Personally, I have six DSD albums. The vast majority of my listening is lossless audio via Tidal. And I'm not just talking about my mobile listening. Tidal rules my desktop as well. So for me, the thinking behind the i-dSp makes sense. Would DSD decoding be nice? Sure. Is it really needed? Not if I'm honest. Your milage may vary.
  
The i-dSp draws very little power, 50 mA to be exact. Speaking of Apple rumors, one can guess why HRT shot for this number... Future-proofing. There have been rumors for months now that the next batch of major iOS updates and Apple devices will slash the maximum allowed power draw from external devices to 50 mA. This is big news for a few manufacturers, as that means several of the recently-released USB-powered wunderkinds out there will no longer work with iOS devices, including HRT's own microStreamer which draws 100 mA. Over a four hour listening period, I noticed perhaps 20% more battery drain when using the i-dSp with my iPod Touch 5g. Impressive.
  
The output impedance is nice and low at .5 Ohm. The noise floor comes in at 8 uV RMS. Plenty quiet for all full-size headphones and most IEMs. As with the microStreamer, I detected some very low hiss present when using the i-dSp with Shure's ultra sensitive 8 Ohm SE846. 
  
Surprisingly, the i-dSp's amp appears somewhat more powerful than the microStreamer's. With sensitive IEMs, this can make for a somewhat limited volume span. Listening with my SE846, I found one bar was my normal listening volume, and two bars was as loud as I generally like to get. Turning to full-size headphones, both drove my 35 Ohm German Maestro GMP 8.35 D just fine. I was also pleased to find both the i-dSp and the microStreamer handled my Audeze LCD2.2 (non fazor) well.
 
  
  
​  
  
The Sound​  
Whenever I'm testing a device that I'm going to end up liking, there's always a moment during a song that surprises me, makes me sit up and listen with renewed interest. 
  
With the i-dSp this happened on Muse's _The 2nd Law_, track one. At around 2:02, Matthew Bellamy howled the title of the track, _Supremacy_, and at around 2:05 the James Bond-esque guitar riff and drums kicked in with a drive and energy that made the arms on my hair stand up. Yeah, I typed that how I meant it. This thing has _mids_. Wow. Just about the best I've heard in a device this small. 
  
This is no small feat. Mids are, in my opinion, one of the hardest things to do right. Boosted bass is easy. Saccharine highs less so, but still not difficult. But the mids... Balancing a rich, full timbre without sacrificing detail. Designing a pleasing shape wherein mids blend seamlessly with lows and highs without becoming murky. This is hard to do. This is rare. There are plenty of great-sounding devices that don't do mids particularly well. Good bass and highs with decent vocals can make up for a lot... Throw in a wide sound-stage and most people are smitten. But there's a reason the really high-end manufacturers strive for great mids rather than cheating. There's an honesty in the mids. Well-designed mids make for a sound signature that doesn't need to rely on tricks. It's a harder way to draft a sound, but the results are purer, cleaner, and just _better_. And because truly well-designed mids are something usually heard in high-end stuff, they evoke a particular reaction in the audiophile ear. They sound... Expensive. 
  
And that's actually an apt word to describe the i-dSp's sound. it sounds _expensive_. Which is fairly bonkers, considering it costs less than, well, anything, actually. 
  
Comparing the overall sound of the i-dSp to the microStreamer, there many similarities, and a few differences. The i-dSp captures perhaps 95% of the microStreamer's signature warmth and grunt, but there is slightly more space and air in the i-dSp. This airier quality is what I believe really untethers the mids and makes them so fantastically effortless and special. The potential is there in the microStreamer, but that extra grunt adds just a little murkiness.
  
Bass is excellent for a small device, detailed and impactful. Well formed with very little degradation in the lower frequencies. 
  
Highs are smooth and a touch dark. Because it lacks that 5% of the microStreamer's grunt, they are just slightly rounder and sweeter. I feel the microStreamer handles splashy highs like cymbals and rattle snares a bit better, but the slightly smoother i-dSp has the edge with plucked guitars and strings. 
  
The i-dSp's vocals are essentially the same as the microStreamers. Very well-placed, neither forward nor recessed, just right. Detail and articulation is excellent. Timbre reproduction is superb. Listening to _The Life Aquatic Sessions Featuring Seu Jorge_ was a pleasure. Jorge has a magnificent voice, managing to move from a sweet falsetto to a deep rumbling baritone to an intimate whisper in a single breath. It's a difficult voice to navigate, but both the i-dSp and the microStreamer handle it very well. 
  
Soundstage is very good for a small device... Managing to slightly widen even the notoriously intimate SE846, something only my Burson Conductor has been able to do, thus far. Impressive.
  
In many ways, the i-dSp reminds me of the Sennhesier HD650. While it's strange to compare a DAC/amp with a headphone, both left me with a similar impression... One of great listenability. Like the HD650, the i-dSp is all about the mids, and all about balance. Both can tame overly dynamic albums without neutering them. Going back to Muse's _The 2nd Law,_ I was struck by the fact that I listened to it three times straight with the i-dSp and my SE846. It's a terrific album, but I've found listening to it on a portable device, particularly with my SE846, is usually not very pleasurable. It's a very dynamic listen, and it can fatigue ears pretty quickly. Not so with the i-dSp.
  
  
  
​  
  
Conclusions​  
HRT may have gone about designing the i-dSp with the average Joe in mind, but what they ended up with is a device that is sure to resonate with discerning audiophiles as well. Simply put, this is an astonishing amount of sound for the money. At an MSRP of $69, it represents the most inexpensive DAC/headphone amp currently on the market, if I'm not mistaken. 
  
When it comes to devices at this price-point I am generally highly skeptical- particularly when they are paired with iOS devices. There is a patently false idea among some audiophiles that "literally anything will improve an iPhone". The truth is, iOS devices represent some of the best sound in the portable industry, bar none. Numerous tests have borne out their superior frequency response and ultra-low levels of harmonic distortion. One is far more likely, when attaching some $99 device to their iPhone, to _lessen_ the quality of the sound. Hell, the odds aren't great with a $300 device. 
  
I've always been of the mind that while it is certainly possible to improve an iOS device's sound with a portable DAC/Amp, it's no mean feat to do so. It takes a remarkable device. The i-dSp is certainly that. Highly recommended. 
  
  
  
  
Thanks to Michael at HRT for taking the time to speak with me, and to Scott and Sean for setting up the loan of the microStreamer.


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## Super Pang

Thanks for that. Can't wait to get mine.


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## Steve Wilcox

I've been frustrated that my Microstreamer will only work with my HTC One (M7) via USB Audio Player Pro, even after updating to Android Lollipop,  I subscribe to Tidal so really need a DAC/amp to work with this and I'm hoping that the DSP will be the answer, especially after reading your review.  HRT Support have told me that the DSP "should" work the HTC One (M7)/Tidal but I'd welcome conformation of this from anyone who's tried it?


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## dfig

I received mine today. With an iPhone 6 on iOs 8.2 and using the Apple Camera adapter and B&W P7 headphones, it simply does not work. I've tried several sets of headphones and none of them seem to make anything happen other than the "this accessory not compatible" screen popping up every 30 seconds or so. It's frustrating. It also doesn't have an LED light like you describe. Even on their Kickstarter page, the project creator confirms that they do not have an LED light.


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## shotgunshane

Have you contacted HRT? If so, what did they recommend?


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## twister6

My HRT dSp review is up: http://www.head-fi.org/products/hrt-dsp-headphone-digital-sound-processor/reviews/12849


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## Dexter Morgan

dfig said:


> I received mine today. With an iPhone 6 on iOs 8.2 and using the Apple Camera adapter and B&W P7 headphones, it simply does not work. I've tried several sets of headphones and none of them seem to make anything happen other than the "this accessory not compatible" screen popping up every 30 seconds or so. It's frustrating. It also doesn't have an LED light like you describe. Even on their Kickstarter page, the project creator confirms that they do not have an LED light.




I'm also interested to hear if you are able to resolve this issue after contacting HRT.


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## Aktersnurra

Got mine today. Works fine with iPhone 6 running iOS 8.2.
The little red light only flashed briefly when I connected the CCK, then nothing.

SQ is not mind blowing but with active listening the musicality and instrument separation is very good. Having said that, the I-dsp is quite easy to forget. I'll use it for workouts when DAP is too much or too valuable to carry. Or on flights where I want to go ultra portable.

And for $69 what can you expect? It's totally worth it!


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## tafens

I got mine today as well (the i-dSp, through the Kickstarter). With shipping and all included it cost just short of $59 total, and at that price it totally rocks  It's top value at its ordinary retail price as well, without doubt 

It works great with my iPhone 5S, iOS 8.2.

One quirk though, on unplugging and re-plugging the headphones I occasionally get the message that the device draws too much power and it gets shut off. If I unplug the i-dSp from the phone and re-plug it it works again. Strange, but I don't expect that to be a problem in normal use.


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## Dexter Morgan

tafens said:


> I got mine today as well (the i-dSp, through the Kickstarter). With shipping and all included it cost just short of $59 total, and at that price it totally rocks  It's top value at its ordinary retail price as well, without doubt
> 
> It works great with my iPhone 5S, iOS 8.2.
> 
> One quirk though, on unplugging and re-plugging the headphones I occasionally get the message that the device draws too much power and it gets shut off. If I unplug the i-dSp from the phone and re-plug it it works again. Strange, but I don't expect that to be a problem in normal use.




Can you describe the difference in SQ that you notice when the unit is plugged in? Another poster said they didn't notice much difference. Thanks!


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## Earbones

dfig said:


> I received mine today. With an iPhone 6 on iOs 8.2 and using the Apple Camera adapter and B&W P7 headphones, it simply does not work. I've tried several sets of headphones and none of them seem to make anything happen other than the "this accessory not compatible" screen popping up every 30 seconds or so. It's frustrating. It also doesn't have an LED light like you describe. Even on their Kickstarter page, the project creator confirms that they do not have an LED light.


 

 Hi dfig, sounds like the first thing you should do is try a different iOS device to determine if the problem is your i-dSp or your phone. 50 mA definitely shouldn't be triggering the overdraw screen on your phone. For what it's worth, whenever problems arise with iOS devices and external audio components, this is always the first thing you should try. Phones can get banged up and internal settings can go awry. Or you might just have a bad i-dSp. 
  
 As for the LED light, you can pretty clearly see the hole on the last picture in my review. It definitely emits an orange glow from this hole. Hard to see in daylight, but noticeable in the dark. Whether this is intended as an LED power light or is simply a hole from which light generated from some internal component escapes, I do not know... I just saw a hole that glows orange in the dark, so I assumed it was an LED light.


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## tafens

dexter morgan said:


> Can you describe the difference in SQ that you notice when the unit is plugged in? Another poster said they didn't notice much difference. Thanks!


 
  
 Well, the difference isn't night-and-day, but the sound becomes clearer, fuller and a bit wider, also bass is tighter.
 This is with my HD590 headphones comparing the built-in headphone out of my iPhone 5S and the output of the i-dSp.
 Using the standard Apple earpods, there's still a difference, but small. Maybe not worth getting the dSp if only using those.
  
 There are a few reviews on it as well that I've found:
 http://www.head-fi.org/t/760209/hrt-dsp-idsp#post_11446510 (in this thread)
 http://www.head-fi.org/products/hrt-dsp-headphone-digital-sound-processor/reviews/12849 (here at head-fi)
 http://forum.xda-developers.com/general/accessories/review-hrt-dsp-usb-dac-usb-otg-support-t3073029
 http://www.myfoxla.com/story/28633023/review-hrt-dsp-i-dsp-definitely-make-music-better
  
  
 BTW, does anyone hane any info regarding what DAC/amp-chips the dSp is using? Would be interesting to know..
  
  
 (edit: added reference to the review in post #2 of this thread)


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## mediabox

My DSP works fine with LG G3 stock player on Lollipop and USB Audio Pro Player, and I am very pleased with the results (Etymotic Research ER-4P). It gives everything more air, enough for any mobile device sound improvement. However, it refuses to play on Onkyo HF Player every time saying that it fails to connect with the DSP and then shutting the player itself down. Samsung Galaxy Tab S (also 5.0) plays well with UAPP, does not work either with the stock player or Onkyo HF.  Compatibility mysteries continue... HAs anybody tried Onkyo HF with the Android version?


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## twister6

tafens said:


> dexter morgan said:
> 
> 
> > Can you describe the difference in SQ that you notice when the unit is plugged in? Another poster said they didn't notice much difference. Thanks!
> ...


 
  
 I usually mirror my reviews between Head-fi, XDA, and AndroidForums and Amazon   So XDA review link (that is the only site where i post under "vectron") is a mirror of my head-fi review from the second link above


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## Dexter Morgan

I wouldn't expect these to have much an effect with Apple earbuds. I imagine they need something more capable of reproducing sound with greater subtlety and detail.
  
 I wonder if the effect is less pronounced with headphones that require more power to drive (over-ears), and more pronounced with less power hungry IEMs. That's my hope anyways, as I would be using these with the K10. For those that have the i-DSP, can anyone test to see if the effect is more noticeable with IEMs versus over-ears?
  
 Edit: Thanks for the links to the reviews, by the way. Will check them out.


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## tafens

twister6 said:


> I usually mirror my reviews between Head-fi, XDA, and AndroidForums and Amazon  So XDA review link (that is the only site where i post under "vectron") is a mirror of my head-fi review from the second link above




*Google lesson #1:* Do not search for reviews when in a hurry. 

(edit: quotes)


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## Lohb

I need to recommend a non-sabre DAC for my friend to hook into a T-amp which goes on to Fostex T50RP's... I think this might be an OK basic starter DAC vs something like a Sabre U2 which is a bit glary/analytical...the T-amp is on the warm side with a slight tubiness to its tone......
  
 I think it may be a good choice ?


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## kostaszag

mediabox said:


> My DSP works fine with LG G3 stock player on Lollipop and USB Audio Pro Player, and I am very pleased with the results (Etymotic Research ER-4P). It gives everything more air, enough for any mobile device sound improvement. However, it refuses to play on Onkyo HF Player every time saying that it fails to connect with the DSP and then shutting the player itself down. Samsung Galaxy Tab S (also 5.0) plays well with UAPP, does not work either with the stock player or Onkyo HF.  Compatibility mysteries continue... HAs anybody tried Onkyo HF with the Android version?


 

 Onkyo HF Player will not work with dSp. It has no volume control of its own, so it can only work with DACs that have some sort of volume control, either digital or analogue.


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## mediabox

kostaszag said:


> Onkyo HF Player will not work with dSp. It has no volume control of its own, so it can only work with DACs that have some sort of volume control, either digital or analogue.


 
 In the latest version they have added - 
_What's New_ _•Support added for volume control of USB-audio-compatible external hardware_
_Volume level of USB-audio-compatible devices featuring volume control circuitry can be adjusted by manipulating the volume keys of your Android device._
 
So is it the HF or dSp?


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## kostaszag

mediabox said:


> kostaszag said:
> 
> 
> > Onkyo HF Player will not work with dSp. It has no volume control of its own, so it can only work with DACs that have some sort of volume control, either digital or analogue.
> ...


 

 I know, I tried that with my Geek Out 450 and a power bank and it didn't work. Maybe because I don't have the Hi-Rez add-on.


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## mediabox

kostaszag said:


> I know, I tried that with my Geek Out 450 and a power bank and it didn't work. Maybe because I don't have the Hi-Rez add-on.


 
 I do have this option, and still it would not connect for whatsoever reason. I wrote both HRT and Onkyo about it. OMG! Now the stock LG G3 player on Lollipop stopped playing... In a nutshell: when it works, the dSp is a beautiful SQ addition for the money, and when it doesn't, well - it is not... Anybody with the Onkyo HF experience?


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## mediabox

*Victor Wooten *A Show Of Hands 15 24bits / 44.1kHz FLAC *UAPP+Samsung Tab S 10.5 +ER-4P+dSp*   What a joy!


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## tafens

Does anyone know what USB/dac/amp chips are inside the dSp? Or is it some sort of proprietary programmable solution? The HRT product page does not say.

It does say this, which suggests either an entirely proprietary programmable solution, or programmed sound processing in addition to a regular dac chip, but which is it: "The i-dSp incorporates proprietary digital Sound processing and conversion along with a high-performance headphone amplifier, all within an extremely portable form factor."

edit: except from the i-dSp product page


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## Lohb

tafens said:


> Does anyone know what USB/dac/amp chips are inside the dSp? Or is it some sort of proprietary programmable solution? The HRT product page does not say.
> 
> It does say this, which suggests either an entirely proprietary programmable solution, or programmed sound processing in addition to a regular dac chip, but which is it: "The i-dSp incorporates proprietary digital Sound processing and conversion along with a high-performance headphone amplifier, all within an extremely portable form factor."
> 
> edit: except from the i-dSp product page


 

 Interested in this too...am guessing they went for TI again like microstreamer which I just picked up last night...I'd like to do both of them head-to-head...'battle of the micro DACs'.


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## lior amsalem

I've placed my order on Amazon but the item is still: Temporarily out of stock.
  
 Also, did anyway have a chance to try the i-dSp with iphone/ipad and newer iOS 8.3?
  
 LA


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## tafens

lior amsalem said:


> Also, did anyway have a chance to try the i-dSp with iphone/ipad and newer iOS 8.3?




Yes, it works well. I have an iPhone 5S with iOS 8.3.


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## mediabox

Tried it with this Japanese wonder for PC - puts things on another SQ level. Before that one has to download ASIO4ALL though.
  
  http://www.head-fi.org/t/705387/bug-head-emperor-player-audiophile-player-from-japan


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## kostaszag

I have been facing a weird problem ever since I received my dsp. I cannot connect another DAC to my cellphone. To be accurate, I cannot connect my Geek Out 450, which I have been using before., the phone will simply not recognize it as a USB device. My phone is a Sony Xperia Z2 running Android 4.4.4. Has anyone had a similar problem after connecting their dsp on the phone?


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## zolom

Yes. Same issue with Headstage Arrow 5P amp/dac on my lg g3 (android 5).
Rebooting the phone enabled to connect the other amp. 
Will contact HRT.


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## Raga Patron

Hi Earbones, you mentioned that the mids on the i-dSp are excellent. How are the mids on the microStreamer?  Are they as good as the i-dSp, or better? Thanks.


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## Lohb

Yes, interested in how well this compares to MS as well....pretty natural sounding entry-level DACs.


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## tafens

Has anyone tried the iDSP/DSP with the Sennheiser HD600/HD650? Is the little thing able to drive them proper?

What about other headphones?

I'm kind of wondering where it's limit is, mainly as it's specified as drawing only 50mA from the connected device..


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## dpmalito

I use my iDSP with Westone 4 earbuds and he sound is truly impressive for a passive DAC costing just 69.99.  With the AMP no where in sight, this is going to be my high end portable solution for now, along with TuneShell to play my 96/24 FLACS.


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## Earbones

raga patron said:


> Hi Earbones, you mentioned that the mids on the i-dSp are excellent. How are the mids on the microStreamer?  Are they as good as the i-dSp, or better? Thanks.


 

 Hi Raga, I prefer the i-dSp mids to the microStreamer's. To quote my review:
  
_"The i-dSp captures perhaps 95% of the microStreamer's signature warmth and grunt, but there is slightly more space and air in the i-dSp. This airier quality is what I believe really untethers the (i-dSp's) mids and makes them so fantastically effortless and special. The potential is there in the microStreamer, but that extra grunt adds just a little murkiness."_


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## CharlesC

Got my idsp this week. It sounds very nice. Truthfully, Apple products sound good anyway but I think this offers a bit of an improvement with my HD598s. Volume is not much louder than straight out of the idevice so I wouldn't recommend this for highly resistive headphones.

Anyway, when I plugged it in the first time a little green light came on but I haven't seen it on in a long time. Don't know if it died or what. Not a big deal. Anyone know what the light is for?


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## shotgunshane

According to HRT, on kickstarter comments, i-dsp "doesn't have a light". But I see it briefly blink shortly after plugging it in. I'm thinking this is just notification of i-dSp making a connection with iOS. 

According to specs it puts out approximately 0.75 more vRms than the stock iphone. To me, it seems about 2 clicks louder overall (with iems). 

I bought one off Amazon, as I'm planning an iOS dac roundup for CYMBACAVUM. I had emailed HRT but got no response, so I fiigured for $69 I had nothing to lose. 

What a nice surprise. It's a great sounding little unit, especially in the midrange. Having very sensitive iems, I immediatley notice a difference in the output impedances of the HRT (less than 1) and iPhone 5S (~2.3). It's subtle but the i-dSP has a bit better bass grip and texture and mids sound a touch fuller. Definitley something to recommend for ultra low ohm iems like the e-q8 or se846.


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## tafens

charlesc said:


> Anyway, when I plugged it in the first time a little green light came on but I haven't seen it on in a long time. Don't know if it died or what. Not a big deal. Anyone know what the light is for?



I thought I saw an *orange* light flash briefly from the little hole on the side once when I plugged it in to my iPhone. The headphones were already plugged in to the iDSP. Maybe an overload indicator? I haven't seen it since though so maybe it was just my imagination.

I guess one would have to dismantle the thing to find out for sure..


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## shotgunshane

I see it blink orange every time I plug it into the iPhone. I'm pretty sure that's the indication of a connection with iOS.


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## CharlesC

You're right. It's orange, brief, and not very bright. Seems to work though.


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## zolom

Same blinking light upon connectivity, with dSP on Android


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## Earbones

Worth noting that while my orange light used to glow steadily, now it just flashes upon connection. I noticed this a few days ago, although I couldn't tell you when the change occurred. Additionally, while the steady glow was very dim, the flash is somewhat brighter. Not super bright, but visible in daylight.
  
 Based on what others are reporting, I'd assume the orange light is indeed a feature, whether it's described in the product information or not. An LED power indicator, designed to flash upon connection to a source.
  
 Assuming an overenthusiastic bit of soldering somewhere in my unit had the LED working overtime... It's figured itself out now, and is working (I'm assuming) as designed.


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## WoodyLuvr

Has anyone tried a 16 ohm rated iem with the iDSP yet?  The low-profile and form factor, as well as the iPhone pairing performance has peeked my interest.


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## kostaszag

woodyluvr said:


> Has anyone tried a 16 ohm rated iem with the iDSP yet?  The low-profile and form factor, as well as the iPhone pairing performance has peeked my interest.


 
 The Sony MH1 I use come pretty close with 15 ohm nominal impedance. The dsp drives them very well, cant  be as loud as the Geek Out 450, but loud enough.


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## WoodyLuvr

kostaszag said:


> The Sony MH1 I use come pretty close with 15 ohm nominal impedance. The dsp drives them very well, cant  be as loud as the Geek Out 450, but loud enough.


 
 Cool; thanks for the reply.


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## tafens

earbones said:


> Worth noting that while my orange light used to glow steadily, now it just flashes upon connection. I noticed this a few days ago, although I couldn't tell you when the change occurred. Additionally, while the steady glow was very dim, the flash is somewhat brighter. Not super bright, but visible in daylight.
> 
> Based on what others are reporting, I'd assume the orange light is indeed a feature, whether it's described in the product information or not. An LED power indicator, designed to flash upon connection to a source.


 
  
 I've checked it again and now I see that the orange light comes on about 2 seconds after connecting the i-DSP to the iPhone, and it stays on for about one second. It's dim though, as you say, and one would have to look for it to see it.


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## Earbones

Just got the new Apple MacBook retina 12", and was hoping the new Apple USB-C to USB adaptor, which looks identical to the Lightning to USB camera adaptor, would work with the i-dSp and allow me to use it with the computer... However the USB end of the new USB-C adaptor is larger than the Lightning USB adaptor, for some reason. So it doesn't fit. Dunno why Apple designed it that way... Bummer. Would have been cool to be able to use the i-dSp with a laptop without some crazy workaround...


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## Lohb

earbones said:


> Just got the new Apple MacBook retina 12", and was hoping the new Apple USB-C to USB adaptor, which looks identical to the Lightning to USB camera adaptor, would work with the i-dSp and allow me to use it with the computer... However the USB end of the new USB-C adaptor is larger than the Lightning USB adaptor, for some reason. So it doesn't fit. Dunno why Apple designed it that way... Bummer. Would have been cool to be able to use the i-dSp with a laptop without some crazy workaround...


 

 Does it actually work in say a Macbook Air with lighting ? I never thought of that !
 Edit : after comparing the ports/plug..I don't think so.


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## earfonia

earbones said:


> *High Resolution Technologies i-dSp* ​ The Mighty Mighty Mids Machine​
> Conclusions​
> HRT may have gone about designing the i-dSp with the average Joe in mind, but what they ended up with is a device that is sure to resonate with discerning audiophiles as well. Simply put, this is an astonishing amount of sound for the money. At an MSRP of $69, it represents the most inexpensive DAC/headphone amp currently on the market, if I'm not mistaken.
> 
> ...


 
  
  
 Thanks for this good review! 
 In your opinion, relatively how much improvement do you hear from i-dSp in comparison to iPhone headphone output?
  
  


twister6 said:


> My HRT dSp review is up: http://www.head-fi.org/products/hrt-dsp-headphone-digital-sound-processor/reviews/12849


 
  
 Thanks for the review!
 Noted this from your review, for dSp comparison with Note4:
 "With my Note 4, sound improvement was less noticeable since my phone has a clean and detailed audio output to begin with, but dSp still provided higher power, less distortion at higher volume, and slightly more open soundstage.  For other people with older phones, especially those who turn their smartphones into a wi-fi streaming DAPs, benefit from a sound improvement will be a lot more noticeable."


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## tafens

lohb said:


> earbones said:
> 
> 
> > Just got the new Apple MacBook retina 12", and was hoping the new Apple USB-C to USB adaptor, which looks identical to the Lightning to USB camera adaptor, would work with the i-dSp and allow me to use it with the computer... However the USB end of the new USB-C adaptor is larger than the Lightning USB adaptor, for some reason. So it doesn't fit. Dunno why Apple designed it that way... Bummer. Would have been cool to be able to use the i-dSp with a laptop without some crazy workaround...
> ...


 
  
 The i-dSp can be used with a computer as well, but a USB extension cable that fits its connector is needed.
  
 I got this one and sanded the plastic down a bit to get it to fit, and the i-dSp works nicely with it:
 "1M 3FT USB 2.0 Type A Female to A Male Extension Cable Cord M/F White for Laptop"
 http://www.ebay.com/itm/251338563929?_trksid=p2057872.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT
 (this sort of cable is also available from other sellers)


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## lior amsalem

Quote: 





tafens said:


> The i-dSp can be used with a computer as well, but a USB extension cable that fits its connector is needed.
> 
> I got this one and sanded the plastic down a bit to get it to fit, and the i-dSp works nicely with it:
> "1M 3FT USB 2.0 Type A Female to A Male Extension Cable Cord M/F White for Laptop"
> ...


 
  
 I've found one that is similar to Apple's connector in size and no sanding is required...
  
http://www.ebay.com/itm/400602940803?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


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## lior amsalem

However, what I do wonder is if one can use a cable like this one to connect the i-dsp to android phone:
http://www.ebay.com/itm/For-Samsung-Galaxy-Note-OTG-Micro-USB-Male-To-USB-2-0-Female-Host-Cable-Adapter-/171793255383?pt=LH_DefaultDomain_0&hash=item27ffad0bd7
 Or this:
https://oneplus.net/oneplus-one-otg-cable


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## tafens

lior amsalem said:


> I've found one that is similar to Apple's connector in size and no sanding is required...
> 
> http://www.ebay.com/itm/400602940803?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


 
  
 Nice tip, thanks for sharing. 
	

	
	
		
		

		
			




 If I hadn't bought and sanded mine already, I'd definately buy this one instead.
  


lior amsalem said:


> However, what I do wonder is if one can use a cable like this one to connect the i-dsp to android phone:
> http://www.ebay.com/itm/For-Samsung-Galaxy-Note-OTG-Micro-USB-Male-To-USB-2-0-Female-Host-Cable-Adapter-/171793255383?pt=LH_DefaultDomain_0&hash=item27ffad0bd7
> Or this:
> https://oneplus.net/oneplus-one-otg-cable


 
  
 Probably. I think, the only difference between the dSp and i-dSp is the packaging and USB input connector type.


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## Earbones

lior amsalem said:


> I've found one that is similar to Apple's connector in size and no sanding is required...
> 
> http://www.ebay.com/itm/400602940803?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


 

 Looks nice, but have you actually tested it with the i-dSp? I ask because the Apple branded USB-C to USB-A female adaptor looks like it will fit the same as the Lightning to USB-A female adaptor, but the female end is actually a larger diameter, too big for the opening of the i-dSP...


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## Jobbing

Backed the Kickstarter dSp project just to be able to connect it to the mini USB of my Nokia Lumia 820. Whereas other mini USB fit very well in the Lumia, the dSp cable keeps sticking out of the port, not sending music through the cable, playing music on the smartphone instead. The dSp+cable work perfectly on my Nokia tablet Lumia 2520. Anyone experiencing similar connectivity problems?


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## lior amsalem

earbones said:


> Looks nice, but have you actually tested it with the i-dSp? I ask because the Apple branded USB-C to USB-A female adaptor looks like it will fit the same as the Lightning to USB-A female adaptor, but the female end is actually a larger diameter, too big for the opening of the i-dSP...


 
  
 Sure, tested to be working.
 I'll post an image later...


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## joshnor713

I gave the dsp (android/PC) version a shot and unfortunately I'm not impressed.  This is using a Nexus 6.  Also, I'm coming from an ibasso mk2 (looking for a smaller solution).
  
 The dsp is missing depth in comparison to the mk2.  I first noticed this with an electric guitar melody, where there's supposed to be subtle echoing.  The dsp is not capturing the feel of sound and it ruins the experience/feel.  Just sounds thin.  I like how it captures all the frequencies and detail, but it's missing body.  So back to Amazon it goes.
  
 Honestly, although it's a tad more detailed then my Nexus 6 output, the Nexus 6 captures more body of the sound.  My 2 cents.
  
 Forgot to mention, using se846


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## techblogpool

I gave HRT a call and was told it is a Texas Instruments DAC but they are unable to disclose the part number.


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## shootthemoon18

joshnor713 said:


> I gave the dsp (android/PC) version a shot and unfortunately I'm not impressed.  This is using a Nexus 6.  Also, I'm coming from an ibasso mk2 (looking for a smaller solution).
> 
> The dsp is missing depth in comparison to the mk2.  I first noticed this with an electric guitar melody, where there's supposed to be subtle echoing.  The dsp is not capturing the feel of sound and it ruins the experience/feel.  Just sounds thin.  I like how it captures all the frequencies and detail, but it's missing body.  So back to Amazon it goes.
> 
> ...


 
  
 Which is better technically? Are there any issues?

 I have a dark headphone (momentum 2), the brightness of DSP might work in my favor.


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## joshnor713

shootthemoon18 said:


> Which is better technically? Are there any issues?
> 
> I have a dark headphone (momentum 2), the brightness of DSP might work in my favor.


 
  
 The ibasso is better by a long shot.
  
 I had the original Momentums (I think the sound sig is close with the 2) and I wouldn't necessarily call it dark.  A lot of the upper frequency detail was there.
  
 IMO, HRT tuned the DSP for boomy headphones, like Beats.  I think with more expensive headphones you start losing important things, like depth.
  
 But the nice thing is it's an Amazon product, so if you don't like it return it


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## techblogpool

I just received a written confirmation from *Kevin Halverson *that the iDSP contains in fact the Burr-Brown (TI) PCM5102 DAC chip.


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## Angular Mo

On my iPhone 6 Plus, iOS 8.3 the device stopped working after a week, I get the "not supported" error message.
  
 I have also contacted supported at HRT and have been ignored.


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## dpmalito

My idsp has stopped working. I upgraded to iOS 8.3 and about 2 weeks later all I get is "unsupported accessory" message. Also my LED doesn't light at all. Anyone know what the deal is? HRT not responding by email. What is the phone number you guys called to get HRT?

techblogpool since you are actually getting a response can you help me and the above poster ?


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## Lohb

Any word on lock-out on this with iOS, I just recommended it to my cousin....


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## h1f1add1cted

Hello,
  
 is there any way to buy this device in Europe/Germany? I only found it on Amazon.com big thanks.


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## Angular Mo

Can I use my iDSP as a line-out to a desktop DAC?


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## CharlesC

angular mo said:


> Can I use my iDSP as a line-out to a desktop DAC?


 

 Provided the desktop DAC has a USB input all you need is the lightening to USB adapter and a USB cable.


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## kostaszag

Mine has ceased functioning. Well, practically. The usb connector has become very loose and every USB cable I have tried gets disconnected at the slightest touch. I have emailed HRT and await response.


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## kostaszag

kostaszag said:


> Mine has ceased functioning. Well, practically. The usb connector has become very loose and every USB cable I have tried gets disconnected at the slightest touch. I have emailed HRT and await response.


 

 A follow up: turns out it was a broken cable. I ordered a replacement, which arrived duly and all is well, but still have not heard from HRT. This is not cool, what will happen if the DAC really breaks or malfunctions? Does anyone ever hear from HRT when you have a guarantee issue?
  
 Now to the cable: I bought this one 
  
 http://vod.ebay.com/vod/FetchOrderDetails?qu=1&itemid=301669713346&transid=1153624847020&viewpaymentstatus=
  
 It works alright, but looks weird when I connect the dSp to my cellphone. So I ordered another one from aliexpress http://www.aliexpress.com/item/USB-2-0-Micro-5P-5Pin-Male-to-Micro-5-Pin-Male-Plug-Short-Cable-Adapter/1912248400.html?spm=2114.031010208.3.60.jdXZZe
  
 It is a bit longer and cheaper too, I wish I had looked there earlier. Will report as soon as I have it.


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## Adam18

I do not understand all the problems that you guys have been experiencing with the i-dSP. I've been extremely happy with mine for over three months now ... No problems at all ! Streaming music from my iPad Air 2 through the the i-dSP has been an absolute pleasure. First, with a pair of Harman Kardon CL headphones...... really terrific sounding music. Then, two weeks ago, an upgrade to the new Sony MDR-1A's ..... Wow ! The sound of music is sublime. 

 Please understand that I'm used to exceptional sounding gear. My main system is a pair of Revel F-12 speakers driven by an upgraded Rogue Audio Cronus integrated amp (with Genelex Gold Lion KT-77 tubes) with a Rega P3-24/Nagaoka MP-150 analog front end and a Rotel RCD-1072 digital deck. My main spot for serious "destination listening" is my music room ... But I gotta tell you, I'm enjoying streaming tunes with my iPad/ I-dSP/MDR-1A's far more than I ever imagined ! First with iOS 8, and just upgraded to iOS 9 ... All is well ! The i-dSP with the necessary Apple CCK is probably the best $ 99 I ever spent during my forty years of being a music loving audiophile. 

I highly recommend the I-dSP. And I also have high praise for HRT ... My e-mails have always been answered within a day or two, with sound advice (pun intended) from the boys at HRT. So do yourselves a big favor and just get this thing ! You will be happy you did. Happy Listening to all !


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## tmauceri

Has anyone had issues with the i-DSP and the new iPhone 6S? I am getting some popping on playback. I also have a HRTmicroStreamer and I noticed the same popping with the 6S. I never had an issue with my iPhone 5S. I also own a Herus and it works fine with the 6S.


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## kostaszag

This is gonna be a long one. After surviving the adventures of post 69 I decided to buy another USB-Cable, a straight one, not angled. That might have been a mistake, for the DSP started malfunctioning again. It could be that the cheap cable I bought at aliexpress had a far too large connector that somehow damaged the DSP.
  
 Anyway, I contacted HRT and had a lengthy exchange of emails with Kevin Halverson (very quick and effective communication this time, no complaints at all), which resulted in me returning the DAC to HRT for repair or replacement. All this happened sometime in Oktober if memory serves. On 04.11 I received a shipping notification concerning a parcel sent to me by HRT. It landed in Germany on 11.11 and was released by German Customs on 28.12. 47 days later. In the meantime I contacted HRT and had (again) lengthy communication with Danielle Buska who did her best to find the whereabouts of the parcel, with no success (I am sure she did her best, but the German Authorities have more in common with immovable objects than some man made institution). Until that day in December when the notification came I had written it of and was quite sure that someone was listening to to good music at the cost of HRT. 
  
 When it finally arrived the parcel contained a brand new HRT DSP as replacement. Many thanks to HRT, especially Kevin and Danielle for an excellent service.


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## Moosi

I've been enjoying HRT idsp for 6 months now. I finally found USB extension cable that fits into idsp. Now it works great with my Macbook air and ATH CKR10 . Wonderful tiny DAC


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## Stafa

Do any knows if the hrt i-dsp can drive the sennheiser HD 650 well? Thanks


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## Stafa

Also, are they better than the fiio k1 even though they're thirty dollars more? Thanks.


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## myemaildw

if anyone selling idsp message


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## Sandman0682

DO NOT BUY  IDSP AND AVOID AUDIO FREAKS
  
 I have had two HRT iDSP models now and both have malfunctioned. Both seemed to develop a loose connection which meant that the audio would dropout and fail to work. For a portable product, it just doesn't make any sense. The quality of these products is so bad that I would not recommend purchase.
  
 It's worth just paying more and getting something that actually works rather than ending up with a useless plastic box that doesn't do anything.
  
 Another point of note is the main UK supplier of the HRT products is Audio Freaks. There are many threads already about the rude Audio Freaks sales advisor who goes by the name of Branko Bozic. His customer service levels are remarkably poor to put it politely, so I wouldn't count on getting a refund when the i dsp fails (which it inevitably will). I would not recommend this product at all, as when it fails, you're probably going to get some rude emails from Branko, as well as no prospect of a refund.


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## Rainmaker91

so... I'm looking at getting a used Microstreamer atm but considering this thing has been released, should I just try and import the DSP instead? I eman it will cost me more than gettign the Microstreamer, but I'm unsure about how they pair up agianst eachother if they were to be at about the same price level.


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## tafens

Stafa said:


> Do any knows if the hrt i-dsp can drive the sennheiser HD 650 well? Thanks



I guess this is an unexpectedly late reply 
But yes, it can drive it and manages quite well for its size and price.

I actually asked the same question in this thread earlier without luck, but recently I acquired the Sennheiser/massdrop HD6xx (HD650 equivalent) and tried the iDSP with those myself


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