Well, if you want to try some really radical 'tweaks' or gadgets, you could give the Peter Belt website a
look.
If you're not familiar with him, he has some interesting ideas about improving
not your system, but the way you hear sound.
Certain hi-fi reviewers rated his stuff very highly some years ago, but not any more apparently.
I did try some of his suggestions, and a free sample of his 'foils', but couldn't notice any difference.
But I see there is some new stuff on his website since I last checked - I particularly like the idea of tying powercords and interconnects into reef knots, and aligning the slots in all the screws in your house!