VR Zone had some quality time with the Asus Xonar D2 sound card and compared it to six other sound cards: Auzentech X-Meridien,
Audiotrak Prodigy 7.1 XT,
Tokyo Style Envy24 HT 7.1,
Creative X-Fi Elite Pro,
Creative X-Fi Fata1ty and Creative Audigy 4.
After hours of testing they conclude that the Xonar D2 from Asus is definitely one of the top sound cards available on the market:
The Creative cards were crippled by lousy Operational Amplifiers and Capacitors and the tokyo style is crippled by lousy opamps, but the Tokyo Style, like the prodigy XT comes with a interchangable OPAMP sockets. Overall, The Xonar comes out top in the looks (bling!) factor and soundstage, but the mids seems to be lacking a little, and domho7 and yantronic pointed out that most audiophiles might prefer the sound that's coming out from the Audiotrak Prodigy XT. The X-Meridien isn't too bad but loses out to the Audiotrak Prodigy XT in terms of Mids.
The Creative cards sounded really muddy on my pair of studio monitors, many of us shook our heads when we compared it neck to neck with the rest of the cards. Some says even the onboard sound of the Asus sounds better.