On January 24, 2018 at 01:47, buzz said...
A given iDevice can only play one track at a time. You can play this track in as many rooms as you like. Note that the iDevice that is currently playing a track must be awake and have a good WiFi connection.
Not from my testing as I reported above, and I just tried again 2 different songs from my iPhone over WiFi to 2 zones and after I started playing I put it back to the lock screen and the display off.
Unless you mean from the headphone jack into the line input on a Sonos device, then only 1 song can be played.
My preferred solution is to add a NAS to the system and store the music there. The NAS is always ON and does not need WiFi. At this point any controller can start a Queue, then be shut down.
The best way to do it.
No problems with WiFi or iDevices being taken out of the building or battery flat etc.