That pcb is such an asshole to work on it isn't funny.
Birgir, apart from all the permutations of different capacitor and resistor substitutions/upgrades the biggest audible change came from the left channel mod.
The one I did went from being a noisy piece of shit to quite listenable.
If it isn't done already I'd definitely do it and leave it at that... possibly change out the HV bridge rec for something decent.