I've actually had this DAC (v2) for about 2-3 months now. I needed something for audio setup for living room, which is basically my NAD C372 int amp, hooked to B&W 684's, and connected to my mac mini and 46 inch lcd. no surround sound, just needed a lsitening jukebox type system for my massive mp3 collection as my cd's have been gathering dust since mp3;s are so much more conveinent.
initially i had my mini connected simply wiht line out to stereo in on amp, and as expected sound was WEAK. volume half way would still not produce any sort of decent sound. I then got this DAC, and as can be expected that alone is a world of a difference. while i realize thats not a fair comparison and most people want to compare DAC's, i dont really have experience with any other dac's and am a casual lister. For me, this little device is perfect, didn't cost too much and produces sound worth every penny it cost. while i do realize the trade off is paying $300 for good sound plus miniaturization, or $300 for possibly better sound in a bigger box, i think in terms of sound this little bugger would be hard to beat in this price range.
I would suggest this to anyone that wants to step up from simple line out to rca plugs. But if you want to replace another dac with this one, i am not sure if you'd get anything in terms of sound quality improvement, for that id defer the issue to some other experts that have given this thing a more thoroughly extended listen than i usually have time for.
The sound ofcourse got better over time as others have commected. The base on this thing is surprisingly heavy. While i sometimes don't trust my own judgement when it comes to audio tests, i do have friends from the music business with very very highly trained ears, andi have heard shocked gasps from them at times when the bass really kicks in as to how good these speakers are. ofcourse we all know without that little dac (or any dac for that matter), these speakers would not produce this kind of punchy sound from mp3's, so this dac does do an amazing job of transporting the sound.
At some point i'd like to compare this to some other dac's in the price range to be more objective and maybe figure out my upgrade path if needed, and i'm pretty sure it will compare favourably. one review online compared this favourably even to approx $1000 dac's. For now though suffice to say as someone looking for a first dac, this one would be difficult to beat in terms of convenience or sound quality. ofcourse the downside is it only works via usb and has no optical in or line in connection which i think other dac's do. I've never really felt id need that anyway.
without comparing thi unit to others, i cant say i know of any downsides as such. while the sound is clean and crisp with good quality audio, there are times when i feel my system could be pushed further and i feel its being underpowered by the source. This could be a limitation of connecting a computer system to a stereo sound system, a limitation of dac's in general, this specific dac, or just simply maybe my amp and speakers not being the best fit together. as this is my first sound system of the non low-end variety, i dont have a cd player hooked up to it so can't compare with that sound, or the sound of other amps and speakers. all i know is that all in all it was a worthwhile investment into this dac, and since i plan to keep my speakers and most probably the amp (unless i can get a rotel) for a while to come, unless it can get substantially better sound from another unit in the same price category give or take a couple of hundred bucks, im totally happy with this unit and setup.