If you want very good sound quality, my recommendation is that you buy a McCormack DNA 0.5 2 channel amp ($900) and use your sony's amp section for the other three channels Your Sony may/may not have the hookups for this. I've heard the McCormack with B&W and thought they were a great match.
Need advice: Budget Amp for system
I just ordered 2 B&W 804's for my Stereo (80%) and HT system. I'm using a Sony STR DA555ES Receiver as a Preamp. It's a 5 channel 80WPC with pre outs. What is the best AMP in the $1200 range that is great for music and good for HT as well ( 5 channel). I love my jazz, R&B, as well as some contemporary music. Two recommeded are Marantz 9000 and the Anthem MCA 5. Any advice would be greatly appreciated.