You could use the fixed RCA outs on the preamp and plug them into a Sonos Connect inputs. The Connect would sit with your main system and the Connect would, well, connect to the Play5 through their own network and you would just control the Play5 through your Sonos app. Pretty easy.
Possible to use Sonos Speaker with hifi system?
I have a old Sonos Play 5 speaker laying around. Is there a way I can hook it up to my system in the living room? Without degrading my 2 channel music quality? It would be for the bedroom when I am walking around the house.
It is:
C12000 McIntosh preamp
861 Moon amp
Eversolo z8 streamer