Best AV receiver to use as an AV pre amp

I want to get another AV receiver, but I want one that has a really good pre section in it so I can also use it well for 2 channel music. I have a Bryston 5B ST that I use for the front 3 channels(and for 2 channel music), but I want to use the internal amps in the receiver for the surround channels only (hence why I can't use *just* a preamp).
I am using my Denon AVR 2808 as the pre now with the Bryston and it is OK, but I feel is really holding it back.
Any suggestions on what would be a go AV receiver that has a great preamp section in it ?