Per TrungT's recommendation and others, I finally got around to wrapping Teflon plumber's tape around the fuses on every component. On the two receivers it was noticeable but not huge. On the bass amp/crossover similar but possibly bigger upgrade then the receivers. CDP can't remember but I think it was just a bit better or not audible.
Biggest improvement on the Trinaural Processor, huge, I was surprised, bigger, badder (in a good way), more transparent, even possibly quieter, bigger dynamics, smoother, estimate 30-40% throughout, no downside for sure.
Might be worth trying on the M51 after it's burned in and you're familiar with it. Pretty harmless mod, easily undone in a few minutes.