First off I'm pretty happy with my DT990.  I like its fun sound signature (especially the bass and soundstage that seems to wrap all around you), and although I can see why some find its treble/sibilance harsh, they don't bother me.  I can listen to these all day and my current setup has been...

Alright this might not seem like a fair comparison, but you might be surprised at some parts.  I'm probably a casual when it comes to audiophiles, so I don't know all the proper terms.  My A900s are a few years old, and the AD2000 is new at over a week.   Setup Primary: PC onboard digital...