It's not the KT88's. I have the F1. Replace the rectifier tubes and the 6922's. I have 1950's GE rectifiers and Ediswan 6922's also from the 1950's (I think). From Upscale audio. The amp is smooth and lush but not mushy or slow. Oh yeah, I changed the Chinese 6SN7's with EH gold pins. You'll love it. Peace and Good Listening, Pat.
