Re: Time to RE-TUBE - PLEASE ADVISE
I think some tubes like E-34L's and KT-77 might work best in 50W amps, since they can always use headroom. But a 100W amp doesn't need it, and a complex amp like a 6100 might operate cooler with regular EL-34's.
I'd probably just use JJ EL-34's since they sound great and are cheap, then spend more on good 12AX7's. I really like the GT12AX7C's for an amp like that. Chinese 9th Generation Shuguang 12AX7's are high output, tight, and focused with gain, and that's why Bogner designed their preamp around those tubes. Sometimes, I'll try other high quality tubes, and they rarely out perform the 12AX7C's. If you want to spend more, the Tungsols are great too, but not nessessarily better.