hmmm.... "O2 needs a very good amplifier"... What is "very good"?
I hope I'll know what is "good" one soon because my KGSS is in progress but for now:
I'm listening to my O2Mk2 through SRM-727II. Both VERY disliked here (shame on stax' engineers!). But I wonder how many people here have been listening extensively to SRM-727II... Yes, it sounded very bland, flat and even muddy with terribly compressed dynamic range at first (there are some threads started by me concerning my complaints) . But after some time the overall sound signature of my stax system has totally chaged. I don't know if it's cans burn-in or amp burn-in, or something else. I don't even know if burn-in question can be related to electrostats. What I'm sure is tha is NOT the so called
mental burn-in 
I'm pretty shure that there is
a real change (maybe I must mention that my amp hadn't been switched off since October 8-th 2009

). Now the sound is very spatious, balanced and detailed. The soundstage is hologhaphic although not so big, the instruments are very life-like and natural. The highs and bass are good although the deepest bass (below 30Hz maybe) misses me. The dynamic range problem was almost completely solved by good balanced ICs - yes, they can improve the dynamics drastically! Now there is nothing in common with the initial presentatnion of this system.
The Omegas are the best allrounder I've ever heard. I enjoy every kind of music with them - acoustic, electronics (especially!), metal and any bad recordings.
I can recommend the O2s with some of the current stax amps for a starting system.
Ergeistpolt, don't be afraid of the stax amps, they are not so expensive and
they drive the omegas well! You won't be dissappointed
