On Friday, 2 September 2016 15:13:36 UTC+1, Bert Coules wrote:
I'd like to be able to walk into any room and select what I hear and the
volume I hear it at from a control (wall mounted, maybe?) in that room.

This chap looks like he's doing something interesting:

http://hazymat.co.uk/2015/04/multi-room-audio-options/

GPIO controlled so an arduino / raspi could be linked in?

Owain