Can I use the Line In on a Sonos Port to send the rear surround L/R signal from my AVR (which has pre-outs for all channels) to a Sonos Amp wired to in-ceiling speakers behind my viewing area?  

For context: I’m moving to a condo that is pre-wired for for in-ceiling speakers in areas that have a drop ceiling (including an area behind the living room which does NOT have a drop ceiling and cannot be wired for in-ceiling or in-wall speakers). The pre-wiring all runs to a utility closet in the back of the condo. I’ll be powering the in-ceiling speakers in the condo with Sonos Amps that’ll live in the utility closet. 

I’m also setting up my “HT” in the living room which will include a Marantz AVR wired to the LRC speakers, the LR surround speakers as well as the subwoofer.  I cannot run wires from the AVR to the in-ceiling speakers or back to the utility closet unfortunately.  It’d be great if I could run RCA cables out of the rear channel pre-outs on my Marantz AVR into a Sonos Port located next to the AVR and set the Sonos Amp powering the in-ceiling speakers behind the living area to play that signal.  Can I do that?