Actually, I've been reading up, it looks like Sonos is the only one (or only one I can find) that actually has RCA inputs for either your receiver or any individual device so, technically I could use my selector switch, go straight into the hub and have it send the signal to a Sonos speaker in the other room. I just have to hope the quality is decent because lots of people seem to talk about it negatively.
MusicCast sounds great, but I don't want to have to buy another receiver.