I got into Hi-Fi headphones this past christmas with an AKG K550 for myself and an ATH-M50 for my brother. When a good friend of mine came over I let him demo them for a while and he really liked them, and expressed he was kind of in need of a new pair of cans himself since the cheap ones he had were in pretty bad shape. He's the kind of guy who would never spend very much on himself, so I got together with a couple of other friends and we've pooled about $150 cash to get him a nice set of cans.
-must be closed back with decent isolation(used on buses and in other vehicles)
-somewhat portable and able to be driven unamped from this friend's sansa fuze
-durable, this guy is pretty rough on his stuff
-good enough soundstage for gaming
As far as music he listens to; it's mostly prog rock, alt rock, classic rock, metal and some dubstep. So a slight bass emphasis is prefered as long as it's tight. When I had asked him which set of headphones he liked out of my brothers M50s and my k550s, he said he liked the louder base in the M50s, but really appreeciated the extra detail, depth and clarity of the K550s especially for guitar.
I live in Canada in the Ottawa area. So headphones are usually a little more expensive than the states or even Europe.
My current thoughts are the Shure SRH840 from here