how does rogue zeus compare cat or atma-sphere?

You are starting with the assumption that the more expensive pieces are as good or better than the still expensive but more reasonably priced unit. In my experience that is a bad assumption.

Pubu157 - Too bad none of us has heard all 3 so we can help with the original question. In any case, no debate with your comments. To the original poster I only intended too share my experience. What I have found is that buying an amplifier is a bit analogous to buying a pool cue. At a pretty reasonable price point a good manufacturer can do everything that can be done for the sake of performance, the important thing in choosing for performance is to find the feel that suits your personal preference. Beyond a pretty reasonable price point (and you can go wayyy beyond if you wish) the purchase is about pride of ownership and exclusivity, just need to make sure that the feel of the cue remains top priority.