By the way, here is very likely a way in which burn-in makes things worse. And it's not isolated, it's quite repeatable, and has been (repeated). Specifically, the line about "...maybe the electrolytic caps are getting leaky (they do get hot inside the chassis)..." being the probable cause for the deterioration of that amp.
EDIT: PS I'm not saying this to push your buttons, piss you off, continue an argument, or any of those things. I say it because I am one of those fucknuts who honestly believes he's heard it (burn-in), and I'm trying to understand it. You guys are smart, perhaps you can explain it to me, most of those fucknuts couldn't explain things to me to my level of satisfaction, because they also believe power cords make a difference, and that's pretty much where I draw the line.
PPS I am also -- other than alcohol and caffeine and allergy meds -- drug-free. Alright, that's a lot of exceptions. Certainly hallucinogenic-free.