That card's really mean for gaming, as stated... it's not the best for music. Aside from the Asus Xonar series, you could consider the m-audio audiophile 2496 (though it seems it may have some driver issues depending on your OS, so maybe not such a good idea
). I was considering both recently but went with a uDAC-2 (USB DAC/headphone amp), and I'm very happy with it. The improvement over my laptop's onboard is like night and day. If you're interested in it or the m-audio, note that they're 2-channel devices with RCA outputs (so obviously they won't support a 5.1 setup like the X-Fi, and you may need an RCA to stereo cable).