Have you ever thought of segregating your surround audio channels so you can assign a particular surround channel to specific SONOS unit? for example: 

Lets say I want to use a RAY and SONOS AMPS for my surround setup. I would like to assign the center channel to the RAY; then assign one SONOS AMP for my Left & Right FRONT channels; and finally

another SONOS AMP for my rear surrounds.( which you already do today)

I cannot use an ARC in my environment as I am space constrained and the ARC wont fit. but my room is larger and I’d like better audio coverage that I think the RAY can provide.

being able to assign surround channels to different sonos units would allow for space issues and provide more sound separation.