I just retubed my 2/90/2 and now I notice a hum from my amp. Obvious answer would be tubes, but it's happening on both sides (only retubed channel A). The hum could have been there before and I didn't notice. It's not a ground loop because it does it without any input. It's more like AC hum.
Would that be some caps going bad? I can live with it, but it just has me worrying, since my 2/90/2 was made in 96.
Maybe it just doesn't know the words.