Pros - Features! Use it as USB DAC, external HP amp, standard DAC via SPDIF, preamp.... all in a really small package - and it sounds good too.
Cons - "Activity Indicator" light on the front seems strange and unnecessary, volume knob on the small side (large knobs are easier to dial in properly)
A while back I was contacted by a representative from Korean based Gyrocom asking if I was interested in reviewing their DAC product. Gyrocom? I had never heard of them. Yet the device doesn’t carry the Gyrocom name at all, but rather is branded as Audiotrak. Now that’s a name I am somewhat familiar with: I’ve heard good things about the portable Audiotrak ImAmp as well as the Prodigy line of soundcards. Apparently there is a group of companies working together under the Audiotrak banner, including ESI which was a popular name in pro audio for a while. Here is a link explaining the situation. The focus of this review is the Audiotrak DR. DAC2 DX Muses Edition. That name is a mouthful, so I’ll be calling it the DX from here on out. From what I can tell the DR. DAC2 DX has been around for a few years, gathering a decent amount of praise from places like Headfonia. What’s new on this version is the “Muses Edition” aspect. The DX features socketed opamps throughout, and the Muses Edition replaces all of them with the Muses 8820 bipolar input dual opamps from New Japan Radio Corporation. Apparently Gyrocom/Audiotrak felt that change resulted in such a significant gain over the stock configuration that they made a new release out of it. At the same time, the old price of roughly $375 has dropped to $329. I hear that the DX is a rather popular DAC in Japan but somehow failed to translate very well to the American market. Perhaps the Muses Edition can change that. DESIGN Even before the opamp upgrade, the DX is a fairly ambitious design for its size and price. Packed in a compact enclosure not much bigger than the Audinst HUD-mx-1, the DX shares many design cues with that device; similarities that made me wonder if the two companies were somehow tied together. They aren’t, as far as I can tell, but both are based in South Korea, so maybe the designs of their devices are indicative of the style trends in their home country. Whatever the case, the DX is similar to the Audinst but much more advanced, and priced accordingly higher. The front panel is dominated by dual ¼” headphone jacks – left side having a gain of +8dB, right side having a gain of +20dB. There is a volume control which applies to headphone out and line out as well as a switch to choose which of those outputs will be active. A pair of switches allows selection of analog or digital input, and USB or SPDIF. Lastly we find tiny LED indicators: one for power that is always on, a row of them indicating the current incoming sample rate, and one labeled “Active Indicator”. That one seems to light up as sound comes through the device, but is fairly dim until you crank the volume over 50%. It seems to act sort of like a VU meter, pulsing brighter or dimmer along with the intensity of the music. I don’t really get the point of it but it certainly isn’t bad either. Around the back we find a plethora of inputs and outputs: Line Out is for use with an external amp, and Line In allows headphone monitoring of analog sources. On the digital side we find coaxial and toslink inputs as well as USB. There is also a toslink output which acts as a pass-through if properly configured – like the Audinst mx-1, the DX pairs well with HTPC applications and allows surround sound signals coming in via USB to pass through to a home theater receiver. Lastly the rear panel has a port for the external power supply. Unlike the Audinst, external power is a requirement. Internally the DX is packing some pretty high quality hardware. The DAC itself is a TI PCM1798. From there the device uses a fully differential output for I/V conversion consisting of 3 opamps, each a dual channel model. The original DX used a trio of the classic NE5532 opamps, but of course the Muses Edition swaps those in favor of the Muses 8820s. Line out originally used an OPA2134 while the headphone out was OPA2604, both of which are now 8820s as well. Note that the headphone out uses the opamp to drive a relatively complex (for such a small device) array of discrete transistors. Other parts are of good quality as well: WIMA condensers, SamYoung LXV series low-ESR electrolytic capacitors in the power supply, and Sanyo OSCON decoupling capacitors. Volume control is handled in the analog domain by an ALPS potentiometer. Here is the list of general specs from the Audiotrak website:
DC 15V / 1A~2A
Dimensions / weight
140(mm) x 111(mm) x 30(mm) / 440g
Type Maximum Out Level Maximum Load Power THD+N Impedance
1/4” Stereo phone jack Port 1 : +8dBV (6Vpp) / Port 2 : +20dBV (24Vpp) 500mW 0.0008% A-weighted (@ 100mW, 1kHz) 0Ω (Load : 16 ~ 600)
24.0V(±12V), FDO : MUSES8820 x 3 (DIP, Socket Type) Line Out : MUSES8820 (DIP, Socket Type) Headphone : MUSES8820 (DIP, Socket Type) Line In : NJM4580 (SMD)
About 4W~6W (5W / typ)
Note the 0 ohm output impedance on the headphone output – this amp section should be good to power even extremely low impedance IEMs without negative interactions. Due to lack of specifics, I inquired about the power output on the headphone jack. I was told that the DX is capable of the following: 500mW at 32 ohms 400 mW at 300 ohms 200 mW at 600 ohms My contact advised that the setup was actually capable of more than 1W at 32 ohms but they felt that may be detrimental to user hearing and/or headphones. Apparently they don’t have experience with the latest planar headphones that can soak up juice well beyond a single Watt. This makes sense if we consider the time frame when the DX was originally released – Planar headphones were not popular at the time. But as I hardly anticipate anyone running an HE-6 straight from the DX, these specs are more than plenty for the majority of headphones on the market. Since the USB receiver is the Tenor TE7022, the DX can handle signals up to 24-bit/96kHz with the exception of 24/88.2 material ( a limitation of the receiver rather than the DX itself). SPDIF inputs are routed through the AKM AK4117VF receiver which can handle up to 24/192. I don’t have anything capable of sending a signal higher than 24/96 over toslink, but I am able to confirm that 24/192 and 24/176.4 work perfectly over a coaxial digital connection. The Muses 8820 itself is an interesting piece. The first time I heard of it was when Esoteric used it in their new D-07 DAC ($4800), a device which I was not particularly impressed with. For a while I recall seeing the 8820 for sale online at ridiculous prices as high as $80. Now I see Gyrocom themselves offering the 8820 on eBay for $9 each which is far more reasonable. Based on specs, the 8820 is not amazing, though it isn’t bad either. I’ve heard various DIY folks talk about how it is crucial to match this opamp with the proper circuit – that just dropping it into most designs will have deleterious effects. I have to assume that Gyrocom knew what they were doing when they chose this specific opamp to replace all three of their original choices. I will say that the Audinst AMP-HP portable amplifier uses the same 8820 in a socket – I’ve tried replacing it with numerous opamps from all the usual suspects, and so far none have sounded as good (in that particular application of course) as the 8820. Tenor TE7022L USB receiver TI PCM1798 DAC AKM AK4117VF Digital Interface Receiver Muses 8820s all over the place Discrete transistors for headphone amp ALPS pot BUILD QUALITY The DX is a well built little box. As I mentioned prior it shares aesthetic sensibilities with the Audinst mx1, and the same applies for build quality as well. Solid but not fancy, the DX has tight fit and finish as well as very well done graphics (which feature prominently along the top of the case). I appreciate that although the rear panel is hurting for real estate, they left just enough spacing for larger interconnects and digital cables to slide into place. Aside from that pulsating LED which I mentioned above, everything works as expected: silent background, no static during volume control, and good channel balance at low volumes even with sensitive IEMs. PACKAGE The DX comes in retail style packaging which reminds me of the box you’d expect from a nice soundcard. That makes sense because from what I hear the DX is commonly found in shops throughout Japan. Inside the box are all the basic accessories one would expect to find: power supply, user manual, USB cable, and a basic RCA interconnect. There’s nothing too impressive but it isn’t lacking either – I’ll simply call it “complete” and leave it at that. EQUIPMENT Here is the associated equipment I used to evaluate this device - I kept things relatively simple this time around. SOURCE: Lexicon RT20 transport, Acer Aspire One laptop, JF Digital HDM-03S music server AMPS: Violectric V200, Analog Design Labs Svetlana 2 HEADPHONES: Audio Technica W1000x, Lawton Audio LA7000, Heir Audio 8.A, Aurisonics AS-1b, HiFiMAN HE400, Sennheiser HD700 prototype SPEAKERS: Serene Audio Talisman Active, Emotiva airmotiv 5 I let the unit burn in for about a week prior to listening. Cables used were from Signal Cable, power conditioning was sometimes provided by Furman (other times plugged straight into the wall). Music used includes a wide variety of genres in FLAC format or occasionally CD, from 16/44.1 to 24/192 and everything in between. LISTENING My first impression of the DX through the Serene Audio Talisman monitors was that it seemed fairly neutral, but with slight tilt towards the musical side rather than analytical. Details flowed freely but were not “in your face” like some devices. The bottom end was pleasing – clearly being limited by the small full range drivers of the Talismans rather than the capabilities of the DX. Mids had an inviting warmth while retaining a nice balance overall. In short, this was a good pairing. I decided to venture out and try different equipment in search of further strengths or weaknesses of the DX. Next came the airmotiv 5 monitors from Emotiva. These active monitors feature a ribbon tweeter for extended airy highs and excellent detail. This tweeter showcased the nice extension on display from the DX – not shouty, bright, or overly hyped, this is what I’d call a natural sounding DAC without veering into “dark” territory. Being musical yet mostly neutral meant the DX/airmotiv combo was as comfortable with the 24/96 release of Kent Poon’s Audiophile Jazz Prologue III as it was with Superunknown by Soundgarden. Once again, a great match overall between DAC and speakers. Having the variable output was certainly appreciated when using powered monitors. Moving away from the realm of active monitors, I figured I should give the headphone amp a good workout. This is HeadFi after all. My initial pairing was the prototype of the new Sennheiser HD700, which should be available as a final release one of these days (thanks again to Sennheiser for the preview – I miss it now that I’ve sent it back). This 150 ohm headphone is nowhere near as difficult to drive as its older sibling the HD800. It doesn’t require the delicacy or finesse in dealing with potential brightness issues. Yet the HD700 does have a trace of similarity in that aspect – it did not pair as well with my brighter amps, and generally sounded best on tubes or smooth solid state designs like the Violectric V200. Similarly, it benefited from having a neutral or just slightly warm sounding DAC in the chain. The DX made a good pairing – slightly warm and musical but not overly so, it brought out most of the quality that the HD700 has on tap. 100% of it? Of course not. The HD700 still responded favorably to a multi-thousand dollar setup. It just wasn’t as much of a requirement as it had been with the HD800. I certainly enjoyed the low frequency kick on the XRCD release of The Joker by Steve Miller Band with the HD700/DX combo way more than I ever have on the HD800 paired with any sub-$500 DAC/amp. I no longer own the HD800 so I can’t comment on how well those match with the DX – but that would be a rather unlikely pairing anyway. Next I moved to the Audio Technica W1000x. This 42 ohm model can easily sound unimpressive or downright poor when paired with the wrong equipment. It definitely benefits from system synergy, perhaps more so than the majority of headphones out there. The DX did a respectable job here but I wouldn’t call it ideal. The slight warmth was fine most of the time but sometimes brought out too much of the mid-bass emphasis that the W1000x can have. And the ever so slightly forward mids worked with some music like Big John Patton’s Mosiac Select release. But in other cases such as Paper Airplane by Alison Krauss and Union Station, the mids felt a little overcooked. The general theme with this combo was that instrumental tracks did pretty well but vocals were just too forward to be pleasing. I tried a few of my higher end custom IEMs and found that the DX was a great dance partner for them. A nice quiet background laid the foundation for a solid performance overall – I especially appreciated the left headphone jack having lower gain than the right, enabling me to have more usable range for volume adjustment. And the extremely low output impedance was also appreciated – even my Lear LCM-2B customs with their wacky 10 ohm impedance rating and 116dB sensitivity sounded excellent with no interactions in the frequency response. This really is a versatile little all in one unit. Lastly, I tried out my latest full size acquisition, the HiFiMAN HE400 planar model. Despite being advertised as being easy to drive compared to the other models in the HiFiMAN lineup, this is still a relatively demanding headphone. The DX seems to have plenty of juice though – in terms of control and dynamics, it matches the Matrix M-stage dedicated amp when driving the HE400 (though the two amps each have their own character traits). I thought that the unit matched particularly well with overall sound of the HE400, which like the DX is all about musicality instead of hyper-detail. At just over $700 for the combo the HE400/DX pairing is an excellent way for someone to get a high quality headphone experience without spending excessive amounts of cash. COMPARISONS Audinst HUD-mx1 The little Audinst has been a favorite in the sub-$200 category for several years now. It still has a soft spot in my heart because it was one of the first detailed reviews I ever did on HeadFi. And to this day it remains a solid performer. What the DX does is build on that foundation, giving a similar overall presentation yet improving it in most areas. Resolution seems higher, low frequency impact is weightier yet more controlled, and soundstage presentation is slightly more refined. There’s no single aspect where the DX blows away the mx1, yet cumulatively the DX belongs in a higher class. I’m currently using the original stock opamps in my Audinst but I’ve done quite a bit of rolling through the various options, and I can confidently say that none of them brought it close to the same level as the DX. I know many people first got into good audio by using the Audinst with their computer as an entry level setup. By now, some of those people may be looking for an upgrade. The DX is an obvious choice since it keeps many of the same features and even the same aesthetic of the mx1 while adding more options and improving the sound. It’s kind of a “no brainer” upgrade unless the user wanted to try a completely different signature. Grant Fidelity TubeDAC-11 In my review of the TubeDAC-11, I called it the best performer in its class, so I obviously liked it better than the DX overall. Is that it then? End of story – buy the TubeDAC-11 over the DX and call it a day? Not quite. As I mentioned in that review, the DX has several benefits over the Grant Fidelity model. Things like USB to toslink conversion and Dolby Digital/DTS passthrough enable the DX to be useful in situations where the TubeDAC would not be. But more than that – the DX is way smaller than the TubeDAC. The DX is nearly half the size of the TubeDAC in length, width, or height. That means it can go places that the larger unit simply cannot go. Places like my cramped computer desk, which can barely fit the Serene Audio Talisman speakers but certainly not the Emotiva airmotiv 5s. When available space is at a minimum the DX is the best option I can think of – better than the Audinst, or the AMB gamma2, or anything else I’ve tried. It’s a case where size certainly does matter. And it doesn’t give up all that much in terms of overall sound quality – many people would have a hard time telling the two units apart. Matrix Cube The Matrix Cube is a solid performer in the $300 price range. It goes a little farther than the DX in terms of musicality rather than detail. By itself I never felt the Cube to be lacking, but in direct comparison to the DX I find it somewhat veiled and overly thick. It retains a slight edge in soundstage size and accuracy and is still a fun listen. But overall it gets outclassed by the DX in both sound and functionality. Again, my Cube does not have socketed opamps, so the newer models may have more potential when swapped with better chips. CONCLUSION The Audiotrak DR. DAC2 DX Muses Edition is impressive on multiple levels. First, the sheer number of features it packs into such a compact enclosure, all of which are done well. Second, the high quality of the audio output through both the line out and the headphone amp is very much above average. Third, the fact that it is comes very close to matching my top pick in this price category – despite the DX already being on the market for roughly 4 years, says a lot. The Muses opamp upgrades are clearly a good choice if they bring the device up to this level. And all this takes place while the price of the unit actually drops by nearly $50. It would be easy to dismiss this little device as a toy. One might expect basic features such as 16-bit/48kHz USB input, a simple headphone section driven solely by an opamp, and not much else as far as options. Instead we get hi-res over USB, a fairly complex and powerful headphone amp using discrete transistors, USB to SPDIF conversion, surround sound passthrough, pre-amp functionality, and even an analog input. I’m surprised, impressed, and very pleased with this device, and I recommend looking into it if its feature set matches your needs.