I was using an EP600 for two channel music along with some tower speakers (Opus 2.2). Then I ended up with a spare set of M80's not being used, so I turned my 2.1 system into a 4.1 system, using the M80's as surround speakers. The sub is crossed at 60. This area is about 26 X 32 and the system rocks. Anyone who says a 600 doesn't work well with music, because it isn't a sealed sub probably hasn't heard one, or is just talking from somewhere dark and stinky on their person. It sounds great, and much better than an sealed Outlaw sub I was using. I've installed an EP400 for a friend and wasn't all that impressed with it. I reckon it would do just fine for an office or small bedroom, but based on my personal experience, that's all I'd consider it for, and most definatley, not pair it with M60's or M80's. There is no way it'll keep up with either. The EP500 is a great sub. I have two of those for my HT room and do not have a want for more.