Hello,
NO current multiroom-system on the market is able to be easy controlled by smarthome devices.
This could be a great feature für volumio / Sound@Home - being able to be controlled by a good documented HTTP-URL interface.
Example: a call of volumio/action/sound/doorBell.mp3 should mute the current playlist, play doorBell.mp3 from local filesystem, and unmute the playlist.
More:
volumio/action/pause : pause current PlayList
volumio/action/volume/up : rise volume by 2%
volumio/action/volume/down : lower volume by 2%
volumio/action/skip : skip current title
…