Hey-Hey!!!,
I would have to ask what it is you want to change the amp into. Clearly you like it as it is, yet it would seem you think it can be better. What does 'Better' consist of?
It looks like a make a change and see what direction it move the amp in is what you're signing up for. Done with enough variables included will mean a lot of trials.
One could beef up the PS, but if it is the PS behaviour dictating some aspect you wish to preserve, it would be counter productive to beef it up as would be traditional with a Hi-Fi set up.
cheers,
Douglas