Not an entirely new component but a major modification upgrade:
External crossovers for my speakers with Jupiter Cu foil caps for the tweeters (I have these) and Jupiter Al foil caps for the mid-range/bass (can't afford these just yet, I need 6 - 12uf).
I also will probably change the inductors, and have to order more Cardas copper binding posts, jumpers, and have some nice wood enclosures built. More $$$. Luckily, my cousin will build the enclosures at a very good price.
But also - in the back of my head - the thought of a custom integrated amp is percolating.