I have a Russound A-H484 Multi-Source Multi-Zone Hub.

I recently purchased a Sonos Amp, and have the speakers in the room directly connected. Works fine.

I would like to connect the Sonos as a ‘source’ to the hub as to leverage the 2 external rooms via the CAT-5 and their own separate amps. 

Is there a way to treat the Sonos Amp as a source to plug into #1 below, thereby then sending signal to the other two channels? (proposed with the dotted red lines). The goal would be to send signals to the 2 external channels.

IMAGE ATTACHED FOR CLARITY.