When I first fired up my test unit, I was pretty underwhelmed with the sound that the Dr. DAC produced. Overall the sound was dull with a bright-ish treble that was downright offensive. Usually this symptom is a tell-tale sign that the unit needs some quality burn-in time. I proceeded to leave the Dr. DAC play music in loop continuously for about 50 hours before doing a formal impression. Well, let us just say the sound was drastically different from my initial impression after the rigorous burn-in session.
Before I proceed, please keep in mind that I am evaluating the Dr. DAC Prime primarily for its DAC function. I feed the Dr. DAC with music from my laptop computer using USB and output the signal via RCA to an external headphone amplifier. I will be evaluating the internal headphone section of the Dr. DAC separately later in this article.
The Dr. DAC overall struck me as a relatively neutral-sounding DAC which is tilted slightly to the bright side of things. This sound reminds me of the DIY AMB Gamma 1 that I used to have which had a similar sound signature but obviously, the Dr. DAC is a lot more detailed and refined compared to the Gamma 1. The treble presentation also has plenty of air in it with plenty of space between instruments. I like this coloration because it is a refreshing change from the other DACs in the Dr. DAC’s price range such as the HeadAmp Pico or Audio-gd Compass that otherwise have a warm-ish coloration.
I am pretty impressed with the magnificent amount of details that the Dr. DAC Prime resolves and it is without doubt that this ability to present details is the Dr. DAC’s strongest suit. I feel that the Dr. DAC is especially tuned to ace this aspect with its coloration: First of all, the Dr. DAC has a rather cold sound that accentuates the treble area which allows us to hear the details in the music better as there is no warmth that can otherwise “cloud” the sound and secondly, the Dr. DAC’s lean sound allows us to differentiate notes between notes and instruments between instruments as clear as day. These “tweaks” also give the Dr. DAC an agile sound that allows it to resolve micro details and transients very well. What is even more impressive that the Dr. DAC manages to resolve this information without sounding rough nor forced and truly, it is a smooth and joyful experience. If you are a detail-freak, I am sure that the Dr. DAC will be more than enough to satisfy your ears.
However, this crazy detail-resolving sound has a side effect which could be bad depending on your point of view and/or musical taste: I find that the Dr. DAC’s low-frequency response to be a bit underwhelming. Do not be mistaken though, the bass is tight and extension is very good but I find that it is a bit too taut as it has too little reverb for my taste. The bass is quite clinical in its presentation and I honestly would not mind trading the tightness a little bit for looseness which sounds very good with contemporary music for that extra bass punch. I am obviously nit-picking here as I suppose that others could live with the Dr. DAC’s bass as it is depending on their mileage. I imagine the tight bass will suit classical music very well.
Imaging-wise, I feel that the Dr. DAC is spot on though the individual differentiation of instruments is obviously not as precise as the higher-end DACs are capable of. Its sound presentation is a bit diffused with the instruments in the center stage taking the most spotlights while the ones in the back and around the central area sound less clear and focused. Once again I am probably nit-picking again here as I am comparing the Dr. DAC to gears that cost 3 to 4 times as much. Given the $499 MSRP the Dr. DAC presents a marvelous price-to-performance ratio.
I compared the sound with and without the 192 kHz upsampling and the differences are pretty subtle which you probably will not be able to pick apart during a casual listening session. With upsampling, the treble sounds a little bit more rounded and smoothed which I suppose could work well if you use a headphone with an aggressive treble.
Finally I would like to briefly touch on the integrated headphone amplifier. This section relies on amplification with 3 dual-channels National Semiconductor LME49860NA high-fidelity audio op-amps. They are also conveniently placed on DIP-8 sockets so you can switch them with other op-amps which present endless possibilities. Using the default configuration, the amplifier section sounds very linear with a touch of dryness that sounds curiously similar with the DAC section. Since the DAC already does a wonderful job in presenting a delectable sound, I suspect that ESI designs the amplifier to be as neutral as possible to show the DAC in its full glory. Power-wise, the amplifier section is not lacking at all as it is able to drive a K501 quite successfully and we know how hard it is to drive this beast. The bass reaches low and treble extension is very good as well. It is also worth mentioning that when I tested the amplifier with a Denon C751 IEM, there was no hiss observed.
I will finish this review by saying that the Dr. DAC Prime is such an impressive complete piece of gear. Other than the lack of marking in the potentiometer, the entire package is well thought-out with clear and logical labels, ease of use, relatively compact size and most important of all, the Dr. DAC looks classy and it will not look odd perching on your work table. This elegance is rivaled with the sound that it produces, whether you use the DAC to feed other amplifiers or its more-than-enough integrated headphone amplifier, the unit pulls through in all of our audio tests. The competition better watches out as ESI has put out a very serious and able product with the Dr. DAC Prime.
System for auditioning:
Headphones: Grado HF2, AKG K501, Denon C751
Transport: Dell XPS M1530
Amplifier: Grace M902