Changing energy settings so "Put hard disks to sleep where possible" is unchecked doesn't work.
The Mac still goes to sleep when Sonos is playing if nothing else is happening on the computer, killing the connection.
Why doesn't the Mac register Sonos playing music from the hard disk as "being in use" thereby not sleeping and just letting the monitor sleep? It doesn't sound too complicated to me.
iTunes works as expected if playing music from the same library. The monitor goes to sleep at the specified time, but the music continues and the Mac doesn't go to sleep.
Best answer by controlav
Thats because THAT APP keeps the Mac awake. The Sonos controller doesn't play any music, the Sonos *players* read the mac file share to get the files then play them. If MacOS doesn't consider that a good reason to not go to sleep, so be it. Nothing Sonos can do about it.