What could i expect between the last technology in the CA M600 vs the Omega 90's technology?
I think the main thing you would notice is that with these last monoblocks, Classe seems to have moved away from the somewhat rolled off and warm sound . If you are using some sort of EQ or room correction,that might not matter so much. Classe's older sound was warmer as well. I like the new sound. The highs sound as extended as I might ever want. The amp also seem very neutral. The newer amps measure very well. The older amps did as well
A lot of Classe and B&W dealers, also carry Mcintosh amps. Over the last couple of years, I have compared both the newest Mcintosh amps vs the Classe. Both companies seem to have changed their house sounds considerably to my ears. Both are fine amps and I could be happy with either. I once was able to quickly tell them apart in sound but not as easily now. I can still tell them apart however. Mcintosh kept part of it's traditional sound but made it more transparent.
Without EQ of some sort, the partnering electronics would be a factor, the preamp for example. Lastly, the older Omega's actually from the Stereophile measurements, have better specs, like SNR. The newer amps is 79db SNR unweighted. The older Omega is 86db SNR, a better spec. The specs for A-weighted measurements also favor the Omega. I don't think, if you didn't know the vintage of Omega, nothing from the specs would give it away as not being one of the most recent designs. In fact, it measure better than some very current designs.