krell FPB300 or jeff rowland model 7

I have heard the FPB series and you can't go wrong. They are one of the better sounding ss amps I have had the pleasure of listening to. I did hear an older JR lower powered amp and it was nice but not my cup of tea. Was not resolute enough. They are seductive but just too laid back or warm for me.

The FPB sounded pretty good initially to me but after sitting with it for a week or two the "Krell" bass was just not there in comparison to the KSA series or even the Pass Lab X series. It has a high number of small capacitors opposed to the few larger beer can type that made it quick on transients but thinner on bass qualities. That was my observation pretty quickly so I sold her her.
Then went on to the Pass Labs X-350 which sounded much more in command as well as bass beefier until I heard the Parasound JC-1 monoblocks and there was NO comparison. I have those to this day and doubt there is much better at even twice the price.

Classe CAM 350's ain't chopped liver either.

what about mark 332.5?

332.5 is another really good amp. I heard the 331.5 which is approx 80% the 334. Personally I would rather have the Levinson than all the ones you mention. I have owned the 27, 27.5, 29, had the 331.5 in my system, and a buddy has the 334. The 334 bests all of the other ML amps I have heard.