[jeffxx]

Hey guys.  I am retiring my DT 770 pros for a pair of Ultrasone 900 pros.  I never learned much about the amp world.  I used a cmoy amp prior to me buying an asus xonar essence stx.
 
I am curious what would be the best setup for this?  I pretty much play all my music through my computer.  Is the asus xonar a good enough dac and should I just buy a new amp?  How would you go about this.   Thanks