I don't know who Bobby is, but the Krell FPB series has never impressed me. I have listened FPB200, 300 and 600. I have found all to be non-involving. Whereas I would say both the Ayre and Plinius are extremely musical, with the Ayre probably being slightly more so than the Plinius. The Plinius will have just a little more bite in the upper midgrange, but is not "steely" and is never harsh. It's always hard to follow someone else's recommendation since no two audiophiles ever agree on everything. So, I guess it is best to hear all three amps (Plinius, Ayre and Krell) and make up your own mind.