That's what I'm using. A central machine (that has an output to main audio system), with it being controllable from anywhere using various MPD clients. I tried

That's what I'm using. A central machine (that has an output to main audio system), with it being controllable from anywhere using various MPD clients. I tried to go the streaming route with MPD to enable music to be played in multiple rooms, but it was very finicky and susceptible to network problems. Instead, another output of the main machine goes to an FM transmitter, and any other audio system can pick it up. The sound quality is not pristine, but it's acceptable. Music in any room, all properly synced and centrally controllable.