I had the FPB600 and the 650monoblocks are a large jump in what the stereo amps do. That is what I have now.I match them with the BAT VK51SE preamp. I did this because I have Sound Lab electrostat speakers. The large varying impedances of the Labs give a lot of amps a fit. The monos have DOUBLE the power supplies of the FPB600.The effertless sound is hard to describe. All I can say is that there is a large improvement using the monos. I had both, this is no joke.As always the front ends are getting better.Spend your efforts there.
