Using a Sovtek MIG 60 head atm. Plugged everything in, standby first etc etc, then turned it on. Played for a little while and it sounded absolutely terrible, fuzzy and so such, not even like it was being amplified - and about a minute in, the back of the head started smoking. Turned it off right away and opened up the back before trying it again. This time, the amp didn't even make the fuzzy sound when I played - it was totally silent. One tube was lit, the other wasn't, so it's pretty easy to assume the tube failed, and there was smoke coming from where it was. Took the bad power tube out and ran it through 8 ohms instead of 16 just to see how it'd take it - no smoke now, but it did light up, so I know it's working, but again, no sound (expected though, since it's not that simple).

Honestly, I'm pretty clear on most of this, but I don't want to replace the tubes until I'm mostly positive nothing else is wrong or was blown out - the reason I'm hesitant is I was getting sound beforehand even with the busted tube there. I believe the term is "crossover distortion." Why wouldn't I be getting some sort of sound, at least? I honestly have no clue what that would be. I'm kind of an electrical nub.

Thanks in advance. I'll answer any questions/clear up misconceptions as soon as I see them posed.
Check the main power fuse. Big chance that one is busted.
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