Depending on your point of view, these are either interesting or confusing times in the audio world because of changes in the concepts behind pieces of audio gear. D/A conversion, server architectures, and packaging for desktop and mobile use are all in flux. The various boxes that do audio things are not static in their conceptualization, something that even computer-oriented people occasionally find baffling. At the same time, the good news is that if you want some particular combination of features to suit your needs, you probably can find it.
NuForce is a brand that seems to specialize in interesting and innovative packaging for high quality audio. The company recently supplied us with a test sample of the Icon uDAC-2, which is basically a USB DAC and headphone amp in a small (2.7” x 1.5” x 0.8”) portable box. The price is $129, and NuForce claims that the DAC compares favorably to that in many audiophile CD players.
That doesn’t sound too confusing, but it took me a minute to figure out what was up with the uDAC-2. First off, the uDAC-2 is USB-powered only (no batteries) and so is designed to work with a laptop, not an iPod or iPhone or iPad (you can use such devices, but you need to interpose a powered USB hub). The laptop/desk orientation is signaled by the design of the uDAC-2, which is a sort of Lilliputian rendition of the NuForce Icon HDP, replete with rotary volume control and RCA output jacks.
I can see several applications for the uDAC-2. If you, like many people, use a laptop at your desk, the uDAC-2 takes up about the minimum amount of desktop area possible while supplying improved D/A and headphone amp functionality. You can also use the uDAC-2, via the RCA jacks, to drive powered desktop speakers as well. Finally, there is also a coax S/PDIF digital output, so you could simply use the uDAC-2 for headphones and let other audio equipment handle everything else.
Then, because the uDAC-2 is so small, you can take it with you on those occasions when you take your laptop on the road. It works perfectly well on an airline tray table, provided your laptop isn’t too big and the guy in front of you doesn’t recline too far. It also covers you in a hotel room or in your mother-in-law’s spare bedroom.
NuForce claims a few special features for the uDAC-2. These a include high quality power supply, a volume control with excellent channel tracking at low levels, an 80 mW headphone amp, and the ability to decode 24 bit/96 kHz USB data streams.
For this test, we used the Sennheiser HD 800, Denon AHD-5000 and B&W P5 headphones as our listening references.
Consider this headphone amp if: you want a mobile DAC/amp with excellent quietness and clarity.
Look elsewhere if: you want to smooth out the treble response of your system/headphones a bit or are otherwise looking to equalize your setup to compensate for perceived deficiencies
Ratings (compared to similarly-priced headphone amp/DACs):
Tonal Balance: 9.0
Output Flexibility: 9.0
As I’ve said before, the subtleties of different headphone amp designs, along with the wide variations in frequency response of headphones, inevitably mean that some of what we hear with headphone amps and DACs is conditioned by what is connected to them. The point here is that the deviations of headphones from neutrality are vast in comparison with the deviations of DAC/amps and so any comments about the sound of the latter relative to the absolute sound will tend to be swamped when you actually do your listening with your particular headphones. That doesn’t mean that DAC/amps don’t matter. In fact, I find that a DAC/amp sets a foundation that can make a given headphone sound more right or more wrong. But your expectations need to be set.
The uDAC-2 supplies an example of this when we start to describe its bass performance, and area where the uDAC-2 could reasonably be characterized as sounding somewhat tight (as in well controlled, but perhaps to the point of being overly controlled and thus a bit lean-sounding at times). Interestingly, this characteristic (and others of a similar nature), can work well with some headphones, but less well with others. For example, the Denon AHD-5000 headphones exhibits a fairly large bass rise, typically producing low frequencies that sound bigger than life, almost to the point of flabby bass sound. The uDAC-2 tends to pair nicely with the Denons, precisely because the uDAC-2’s slight degree of low-end tightness tends to mitigate (or at least partially mitigate) the Denon’s bass excesses. But my underlying point is that, when listening to the uDAC-2 or any other electronics component, it’s important to distinguish between the relatively subtle sonic characteristics imparted by the electronics versus the typically much larger effects of the transducers you’re using. In this review, I’m trying to separate out the distinguishing or defining characteristics of the uDAC-2, itself.