I'm not sure if I'm out of the woods yet, but I found my adjustable NFB resistors were uncomfortably close to a ground tab. I moved them and now the amp, as far as I can tell, sounds great. I'll give it a more thorough run-through for sure.
I had hoped to record the outage I was hearing and recorded a whole new noise issue instead. If you're interested, here's what it sounded like before and after, complete with unpolished guitar
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
Before chop sticking (BONUS: hear the difference in minimum tremolo speed between stock bypass cap and a red LED): After chop sticking (BONUS: Hear different pickup/NFB settings while pushing the PR circuit--no pedals, just the amp): All of your help is indeed much appreciated. Looks like I may have a spare PR OT for another chassis.
![Rolling Eyes :roll:](./images/smilies/icon_rolleyes.gif)