Terry Kath of Chicago is one of the best if not the best, old Chicago rules.
"But I like a good fast sound with lots of space and imagining is very important"
In my humble opinion there is little that competes with Magnepan given your above statement, they are fast, actually super fast, accurate, detailed and once correctly set up literally can't be beat in most opinions without spending 3-4-5 times as much. I traded out a pair of Paradigm Studio 40's and a pair of B&W 604's for the first pair of Maggies I owned, the MMG's, and at $599 retail direct from Magnepan they blew the doors off the above speakers. Take another listen when you have a chance.