Features (listed from coolfungadgets)
•High speed USB connection
•Independent power module provides pure and strong power supply
•Independent APU MU6010 for 24 bit/192kHz audio processing
•High quality S/PDIF transmitter
•Optical toslink & coaxial RCA digital output
•Stereo RCA, 3.5mm headphone analog output
•Headphone 1 is for medium/high resistance headphones
•Headphone 2 is for low resistance headphones
•Support 24bit/192kHz digital output
•Specialized ASIO driver - support Windows XP, Windows Vista and Windows 7
•Aluminum alloy chassis for minimum interference
I have been using my X-Fi for 3 or 4 years now. I've also upgraded the opamps to LM4562 (improved high end details and transparency over onboard sound, less edgy but vocals still sounded a bit "digitalized" if you get me) and decoupled the capacitors for about 2 years now. The 02 US sounds like an improvement far greater than the jump from onboard sound to a modded X-Fi, to me it really felt like the next step.
I don't really feel like there's any point in comparing my onboard realtek "high definition" audio as it's fairly low end (harsh, lack of resolution and dry) such that my zune and sansa clip sound better (greater dynamics , greater soundstage and generally more detailed)
I mainly listen to rock,alternative,classic,electronic,piano pieces and once in a while pop just for the heck of it
It has a very solid casing, very study and not made of thin metal.
Sound comparison
02US vs opamp upgraded X-Fi Xtrememusic
Headphone used : Grado SR-225 (X-Fi cannot drive my HD580 adequately, sounds quite anemic I should say)
No dedicated amp was used
Speakers : M-Audio BX5a
The first thing apparent between the two is the instrument decay and texture. For the X-Fi I can't distinguish timbre well at all , the 02US really fleshes it out for a violin,saxophone,flute,clarinet and piano for example. As I know, it is not only the pitch or tone that makes me able to distinguish an instrument, it's much of the texture. The X-Fi has wide soundstage compared to onboard, however the depth is further improved on the 02US as well as the width ( the depth was a more noticeable change than width). Instruments have a more apparent occupation in space; X-Fi sounds cluttered in comparison. The vocals on the 02US are great, and sound natural without a hint of edginess or graininess. The X-Fi presentation of vocals ( can be smooth and rough at times) vary through a variety of recordings but the 02 US manages to keep its smooth vocal characteristic a constant. I didn't notice anything too different about the distance of vocals between the two sources. Everything sounds so well together, the layers of instruments and vocals blend in together well without losing any detail and does not become a mess. It is really a bliss listening to vocals on the 02US unlike any other sources I have
The 02US is able to be very detailed (again the decay and timbre is beyond the X-Fi) and crisp in even complex passages where the X-Fi loses midrange detail and separation creating a small mess. Like many source upgrades, I find myself hearing new details and for details that were already there, stood out even more. The separation in the strumming of an acoustic guitar for example is good on the X-Fi but 02US manages to bring out even more distinction between each pluck. Also passages of music pieces when the choir comes in, the 02US makes it noticeable there are more singers there with the choir; the X-Fi makes it seem as if the choir is short a few voices. The 02US is easily able to dissect small details and present them, where the X-Fi isn't able to discern them at all.
The 02US is able to keep its composure of sounding smooth, detailed and transparent at all times. Although the 02US is smooth sounding, it is capable of making guitars in rock sound lively. Drums have a dynamic snap and cymbals actually shimmer. Pianos notes have body, tone and decay not distinctively apparent on the X-Fi. I can't stress how smooth flowing the sound is compared to the X-Fi, it really needs to be heard than described. It does so without being mellow,boring,overly gentle or lacking in dynamics, and has rhythm. I can even listen to the 02US at a slightly higher volume because of how non-fatiguing it sounds.
Regarding the highs, I have always wanted more out of the X-Fi despite the improvement by replacing the opamps. It didn't have that sparkle and is tad shrill. 02US remedied this for me, violins really "sing" and something like a triangle instrument had the sparkle on its initial hit. Lastly, the low end frequencies on both are comparable but in terms of impact the 02US has the edge creating greater dynamics which is nice for kick drums for one. Bass in some songs had a tighter and more controlled punch to it compared to my X-Fi which is more loose.
If I had to pick a word to roughly sum up both sources
X-Fi : Artificial
02US : Natural
Musiland 02US is competitive to the uDac. Musiland 02US has slightly more forward vocals, more extended high and better bass impact and depth. This comparison was made through my Arietta amp
02US is one of the best value DACs I have owned. Those with harder to drive cans may want to pair this up with a proper amplifier.