Thoughts on Krell FPB series? 600 in particular.

You should put the jumpers in when using single ended or unbalanced connectors. It doesn't matter using tubes or not. Jumpers are not used with balanced which makes sense.

Thanks JWM. And you didn't experience any degradation in SQ, per the above comments?

No not at all. Your other alternative would be to use a Balanced to RCA adapter, but then you have an adapter.

I had a FPB 600 for years and compare to latest SS, it's a bit grainy and dark but still a terrific amp. The only reason I sold it is to try something different. It sounds great with everything include 100 db Avantgardes. You can hear and feel stability of the sound.

When I play the track The Four Seasons, never achieve the level of dynamic swings since the Krell shivering my whole body. I'm in the camp never too much power and dynamics is what make music fun for me.

FWIW, I found network cables such as MIT worked best with all my Krell amps. I only use tube preamps with them and XLR offers the best SQ.

Knghifi, could you elaborate more on how you define "grainy"? Curious whether I can hear on my FPB-250m what you heard on your 600's.