audio reseach ref 3 or krell KTC...?

Ckoffend, get the upgrade done to 400cx..that was my favorite FPB amp of all (better than monoblocks). Krell ended their golden age of audio design with the FPB cx series amps! You must get a Transparent MM reference power cord for it..you will crap your pants after hearing how huge a difference it can make.

Dave_b, why is the 400cx better than the 450mcx? As far as I know it is the same ampliifer with a single channel, but the power supply of each 450mcx has the same power of that of the stereo CX.

I think it would generally make more sense to just buy a 400 CX versus having the upgrade done. I think from a cost to resale relationship this would be better economically. I'll listen to the 300 C before making any decision. I certainly don't need the additional power, but am always interested in anything that will improve performance.

Microstrip, ckoffend...not better but slightly more laid back and less aggressive in the upper midrange. Krell monoblocks have always had a bit more hardness and leanness in the upper mids compared to the stereo units! By the way, the FPB300 will actually sound more rounded and "tubelike" compared to the 400cx so maybe standing pat will be more your cup of tea anyway..depends on the synergy of your system and cabling. Bigger power supply in 300 vs later models and 400cx!!