the two points on which the Monitor 02 kills the competition are:
1)-external PSU, even though it's a cheapo SMPS...it doesn't need the filthy 5V from your dirty ATX PSU(HDD's make the 5V/12V jitter go up the roof apparently)
2)-bit-perfect/automatically bit-matched async USB drivers up to 24/192 in KS/ASIO....a cheapo PCM27xx TI chip is 16/48 max, uses the crappy windows built-in audio USB protocolol(no KS/ASIO)...and god knows how the sample rate matching occurs(I could easily foresee windows resampling everything @48kHz

)
about SQ? not sure...but 32 bit digital volume attenuation will always kill a crappy analog pot.
if I don't like the SQ on the 02 w/ my cd1k(same drivers as cd3k), it'll be about time that I get one of these sexxy chinese tube amps

but apparently it's very solid on easy to drive headphones...don't expect miracles on an hd650 or k701, though.