Well, although my VA2 sounds pretty good, I´m planning to replace the old CXA1034 by the AN7108. A much better chip indeed. Also I want to CXA2075 mod it.
I too am modding a VA2. I've always wanted to add both a Jap/Eng and 50/60hz switch on it. The only hard part is acctually finding the parts.
I'm in the process of recapping my Japanese VA1 Mega Drive. I replaced most of them yesterday and now I need to get some more caps before I can finish the whole thing. Both the video and audio quality went up so I expect even better results when the whole system is recapped.
I'm currently cxa2075 modding my VA2 Genesis 1. Just have to tweak RGB a bit and I'll be ready to go.