Great deal. Have had one of these for a couple months now and very pleased. I have had many soundcards in the past as well as DIY DACs and amps and this is by far the best combo for the money if you are on a PC. Drives my HD580s very well.
I have had many XFIs and their amp circuit is decent though I replaced the opamp. It drove my HD 580s just fine. I would look into a set of used HD 600s or similar, maybe Goldring DR150. Try those with your card first before getting an amp.