how does rogue zeus compare cat or atma-sphere?

It might be hard to come by someone with this particular audition. I doubt many CAT owners would consider Rogue as an alternative to replace their CATs (not that the Rogue might not in fact be a giant killer - and I do agree with Oem's comment).

Pubul57,Looking at your system,you have SLAIN THE GIANT.Great Gear,happy listening

i've heard the cronus(integrated) a/b'd with some big names and found it to be close. its sweetness reminds me of the classic marantz 8b, which is the biggest compliment i could pay it. there are many expensive tube amps out there that are just a bit better...but in this hobby of diminishing returns for what you get soundwise, i suspect the zeus, like the cronus does comes as close as any giant killer.

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.

I would think it would be hard to compare the zeus and cat with the atmasphere amps as it would be transformers vs OTL;which are 2 completely different species of amps with completely different designs.
If you were driving a 16 ohm speaker my money is on ralphs design (atmasphere) and I think it would win hands down over the other 2.
If the speakers impedance curve dips below 4 ohms I would think it would be a very close match with the CAT probally winning; thats my opinion though.
You should compare for yourself and see what happens;probally would be a good learning experience.