something like the audiotechnica ad500x, 700x or 900x paired up with a soundcard and a modmic would be good. an alternative would be akg cans like the q701. wide soundstages.. detailed and crisp bright highs with almost no low end bass extension. perhaps not the most fun to listen to but will give advantage in fps gaming. you have your choice of going with a soundcard or soundcard outputting to an external amp (which would give you an analog knob to turn for volume). the ad's arent too hard to drive so big amps are not required and soundcards alone would work perfectly fine. akg cans however can be difficult to drive so may certainly benefit from a good external amp.
the ath-adg1 is the ad700x in headset form and is vastly overpriced...