surround processor?

If 2-channel is very important to you, IMHO it’s best to use a dedicated stereo preamp or integrated and hook the front L/R preouts of the AVP into it. 

soix, I assume in the setup you describe the AVP is out of the loop for stereo, but its L/R preouts go to by-pass inputs of the preamp for surround. That’s the setup I use. HDMI input to a Bryston SP3, balanced analog from the SP3 to an Ayre preamp. Balanced analog stereo inputs go directly to the preamp, so the SP3 is out of the loop.

Best to have two separate systems, sharing only some sources if desired.
Then you can enjoy surround AND the best of stereo that you can muster.

Recently i began a search for components for a music only 2.0 system. The heart is a Parasound Hint6. It had a feature i dont use the HT Bypasss feature that lets me use the Hint6’s 160watts per ch amp for either music or HT.

so, you could use one of those horrible sounding multich receivers in attempts to recreate what the director intended, or just wall of sound it like some people do, stereo is fine for some folks year round

A good option would be to get a used Classe Sigma SSP MKii (if you can find one as they are out of production). The 2 channel function is based on the highly rated Classe CP 800 preamp. There are probably better options if your focus is 7.1, but it performs well enough and the 2 channel is very good through the USB input or analog XLR. I use a Lumin streamer and connect it via analog XLR with the Sigma in bypass mode.