DT48 fits all your criteria minus the bass roll off..
Oh my... I'd get the HP-2 but they are open cans. I need closed cans. Hmm, all I want is a flat frequency response, fantastic sound staging, extremely low sibilance (or even non-existent), no roll off, and really good isolation. Anyone have any other suggestions?
Yes... I am difficult to please hahaha. I appreciate you guys helping me out by the way. I want everyone to know that I value my place here! I LOVE this forum.