Review: HRT dSp & i-dSp Definitely Make Music Better

In the world of mobile high-end audio, the DAC is a powerful component in the chain of hardware that gets audiophiles their sonic fix. First you have the audio recording, most likely a digital file of some sort and most commonly .flac or .wav if we're talking high end. You're going to play that on a laptop, or tablet, or smartphone. To get the most out of listening, you're going to need some quality headphones. The problem though is that your mobile device may be the weak link in that chain. You may not always have the creme de la creme of audio processing chips inside of your device. So a DAC, or digital-to-analog converter, is the route many hardcore music enthusiasts go to get the best possible sound from their device to their ears. Beyond the realm of the audio enthusiast, these DACs are often very expensive and outside the reach of most casual music consumers. That's all changed now that a company called High Resolution Technologies has introduced their $70 dSp and i-dSp DAC s .

The dSp and i-dSp are device specific- I'm betting you can guess which model works with which devices. The former works with laptops and all Android devices that support USB audio out, running Android 4.0 or better. HRT says the units work best with Lollipop which natively supports USB audio out. It will also work with iOS devices running 6.0 or better via the Apple camera 30pin to USB connector kit. The latter, the i-dSp, works with lightning connector iOS devices but also requires the Apple lightning to USB camera adapter. Using one of these DACs couldn't be any easier! They are truly plug-and-play. Just plug the appropriate DAC into the USB port of your mobile device, plug your headphones into the 3.5mm jack on the other end and enjoy your tunes. It either works, or it doesn't. Your smartphone must support USB audio out in order for this to work. I tested it on a Galaxy Note 4 (which, coincidentally, already has a pretty good built-in DAC), Macbook Pro, Asus Chromebook c720 and iPad Air.

This is how it works. Once plugged up, the mobile device sends the raw digital audio data directly to the dSp unit, which turns that into an electrical signal while also amplifying it out to your headphones. That simple. What that means for you is this: if you have a pair of very high end headphones which your smartphone is not completely capable of pushing the full volume of music through, you'll now experience that music fully the way it was intended to be heard. You'll get music more nuanced and, in this case, with more volume. At least, that's the idea.

So, at only $70 does the dSP do what it purports to? Does it make your mobile music better? The short answer is a resounding "yes." Matter of fact, it will make all of your music sound better. Using Audio Technicas new high end ATH-MSR7's, I tested the units with multiple mobile devices. Plugging the dSp up to my Macbook Pro gave my music more ceiling, more sound separation and greater amplification. Listening to AAC files in iTunes that were encoded at 128mbps and 44kHz in the .mp3 format produced markedly better results. Tracks had clearer more crisp highs, better separation between the highs, mids and lows and I could even pick out small nuances in the music that were inaudible before. Though the sound from high bit-rate .flac files was not as strikingly different, there was definitely a difference when I was actively listening as opposed to passively listening.

The track "Down By The River To Pray," had a more pronounced ethereal feel to it. It sounded "bigger," like you were listening in a large venue with a huge acoustic ceiling like the Hollywood Bowl. "Down By The River To Pray" sounds like that without the DAC but it was definitely more pronounced with it. As far as the Note 4, the experience was the same as listening to the .flac files. In terms of sound quality, music was more nuanced but the amplification was noticeable. Streaming the Skrillex remix to Benny Benassi's Cinema, the dubstep "growls" and hits were more pronounced. Overall, the sound out of the phone was just more robust. And this experience was consistent across all of the devices I tested.

I have a buddy who is a music producer and synth enthusiast so I thought he'd be great to give the i-dSp to. When he brought it back to me, the first thing he said was, "I couldn't stop listening to it." He told me that he literally sat for hours listening to audio through the i-dSp and playing tracks with and without the device and was consistently amazed by the difference in quality.

One of the things I think that people will be struck by when they first open up the packaging and take out either the dSp or i-dSp is the build quality. It feels "cheap." Both versions have plastic bodies and a slight rattle that belies the actual quality of the product. I'm not a serious audio enthusiast, but if I was I would run to my computer and buy this right now! For the cost and the bump in audio quality on low bit rate music, the dSp units are a "no brainer." Kudos to HRT for bringing a product to market for people who really want to enjoy quality high bit rate sound but don't have the disposable income to purchase some of the higher end mobile DACs. And, if you're an audiophile who travels frequently but fears losing an expensive DAC, this is a great option you should consider.

Sample rate up to 96 kHz
Bit depth up to 24 bit
Full Scale output 1.75 Volts RMS
Output impedance .5 Ohm
S/N Ratio (A-weighted) 106 dB
Noise floor (A-weighed) 8 uV RMS
Frequency Response (20 Hz / 20 kHz) +0 dB / -.2 dB
Power requirements 50 mA
Dimensions 2.1" x .80" x .30" (dSp)

3.4" x .81" x .50" (i-dSP)

Weight .2 ounces (dSp)

.4 ounces (i-dSp)