whether to upgrade Anthem AVM30/MCA50

My system consists of Thiel 3.6's, Snell center & surrounds, Cambridge Audio 852 player, Anthem AVM30 & MCA 50, Cabledyne cords & interconnects, and Pioneer Elite 1080p 50".

I am most interested in 2 channel audio quality.

I'm considering upgrading the preamp to an AVM 50 or the D2V, and the amp to an A5 or P5, or just add an A2 or P2 for the Thiels.

Anyone have a sense whether any of those would provide a worthwhile audio upgrade?
If your main concern is 2 channel, I would say get a good 2 channel preamp with a HT passthrough. That will give you a huge increase in sound quality and you will still have your theater.