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HRT DSP / iDSP

Mar 24, 2015 at 3:41 PM Thread Starter Post #1 of 79
Earbones

Earbones

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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!
 
Mar 26, 2015 at 3:55 AM Post #2 of 79
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.
 
 
 
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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:
 
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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. 
 
 
 
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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.
 
 
 
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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.
 
 
 
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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. 
 
Apr 1, 2015 at 3:55 PM Post #4 of 79
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?  
 
Apr 3, 2015 at 11:15 PM Post #5 of 79
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. 
 
Apr 4, 2015 at 10:38 PM Post #7 of 79
Apr 7, 2015 at 1:44 AM Post #8 of 79
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. 
Click to expand...


I'm also interested to hear if you are able to resolve this issue after contacting HRT.
 
Apr 7, 2015 at 11:08 AM Post #9 of 79
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!
 
Apr 7, 2015 at 2:58 PM Post #10 of 79
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 :D 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.
 
Apr 7, 2015 at 4:20 PM Post #11 of 79
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 :D 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.
Click to expand...


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!
 
Apr 7, 2015 at 7:03 PM Post #12 of 79
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. 
Click to expand...


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. 
 
Apr 8, 2015 at 5:14 AM Post #13 of 79
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!
Click to expand...

 
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)
 
Apr 8, 2015 at 8:26 AM Post #14 of 79
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? 

 

 

 
Apr 8, 2015 at 11:29 AM Post #15 of 79
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!
Click to expand...

 
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)
Click to expand...

 
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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