The amp in my avatar is making a somewhat intermittent frying bacon or static noise. Google suggests sizzle is typically pre tube related. I’ve swapped tubes, but the noise still shows up. It’s a simple grid-leak bias input design, if that matters in this situation. The sizzle first occurred when I tried a wah with it. It was very loud and sudden. Scary enough that I just turned it off and put away the wah. It did it again with a drive pedal, even at low to mid volume. I swapped the original tube for an original RCA from my SF Champ. Since then I’ve noticed it only occurs at higher volumes without any pedal. And it’s not loud, at first. I purposely have not used any pedals since then, though. The original tube from this amp is in my Champ, and appears to be ok. With my MIM tele with stock pups, and no pedals, the noise typically begins to show when amp volume is loud enough for output tube crunch, and only when playing. The amp has otherwise no excessive hum, with or without guitar and/or cable plugged in. Hum is imperceptible at low to mid volume (kinda cool that way, actually). The sizzle/static noise is unrelated. Once the sizzle starts it gets louder, worse and worse, until there is only loud sizzle. By that point it is consistent and occurring without me playing. I have to shut it off then. I’m wondering if it’s heat related? If I wait a while to turn the amp back on it seems back to normal. I can play it low volume. But if I crank it up, and play it, it’ll eventually start to sizzle. Just a tiny bit at first, and only in reaction to input from me. Like I’ll play a note, and there will be a hint of static with the note. If I keep playing, it just gets worse from then on. So, sizzle or static sound that appears to be related to input, affected by volume, but maybe not tube per se(?). What all should I be checking for?