if you are considering the hd558 it would be a very worthwhile jump to go to the hd598 at $30 more than your budget. they are very highly respected and have a huge soundstage. it doesnt have much bass presence though but typically enough for gaming if you arent a basshead.
the hd558 however isnt a bad choice but its not going to be on the same level as the 598. the bass is a bit more punchy than the 598 but it doesnt quite have the clarity of sound.
the ad700x by audiotechnica is also great and has a wide soundstage and mid/high focused sound. again, it doesnt have much bass (as in almost none).
the dt990 tends towards mid/highs as well but does have fair bass on some of the models although nothing like some of the monster closed...