It’s not just Power Tubes.
My 6sl7’s made a big difference. (your A100t uses 1 6sn7 and 4 12AU's)
Originals: Labeled Cayin Brand, unknown maker, sounded great.
blew one (put in wrong socket), I wanted a matched pair of 6sl7’s that had a different appearance so I could not put one in the wrong socket.
Chose 6sl7WGT brownbase, chrome top, military matched pair.($80. each in 2020).
Nooooo. Wrote Brent Jesse, he had me break them in (amp on for 60 hrs, no signal needed), broke in for 3 days, still a no go.
Returned, full refund except shipping cost.
Tried 6sl7gt, General Electric, side getter, cylindrical plates ($40. each in 2020). They sound wonderful, as good as the original Cayin branded ones.
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Power Tubes
My amp came with 6550 Gold Aero, they sounded great. I have a set of 6550 EH Electro Harmonix, matched when new, but used,
I wanted to try new matched KT88’s, went for KT88’s Blue JJ Electronic, I prefer them.
