Using an AVR as a pre/pro will really limit the performance of a good amp, trust me I know, I used to run a Pioneer Elite AVR feeding a Parasound New Classic 2250. When I finally upgraded to a dedicated 2 channel preamp with HT bypass (Cambridge 840E) I noticed a HUGE improvement in performance, the AVR was the weak link in the chain.
The next big improvement in performance came when I replaced the Parasound with a Odyssey Kismet 2 channel amp. Do your self a favor upgrade your pre/pro before getting a new amp.