I've got Audio-Technica A900s, so the closed cups not open. I can vouch that they're a good entry level 'phone. I hardly ever use them for listening anymore, but they did alright with Hip-Hop, psychedelic - not out of this world or anything, though. Although I haven't heard the AD900s, I imagine the closed cups would have a little more thump in the bass than something open (perhaps someone who's done A/B on these could comment a little better). These days I mostly use them when playing MW2, the details are crisp - makes it easier to hear people sneaking up on you.
I just want to qualify my experience with the AD900s a little more. The bass is moderately punchy, ample but not mind blowing, and I wouldn't exactly call it "crisp." The vocals and upper end are a little muddy. It's well rounded but doesn't shine brightly anywhere.
I'm not big into chatting while gaming tho, so a separate mic does the trick pretty well for me. Right before I edited here, I saw the poster below me comment on tangled wires with headset vs. seperate mic. I think it all depends on your setup, I've never had a tangling problem. It all depends on what your source is...