Mike would like to be able to control multiple speakers in an open house with his iPhone. Is that doable? Leo says that the key is keeping all the speakers in sync. Sonos was the first to do it right with multi-room sound. All speakers are completely wireless and can be put into party mode, where all are playing the same music in sync. Sonos isn't cheap though.
Other options include using a portable Bluetooth speaker in each room. They can connect to the iPhone together. Leo recommends Bang & Olufson and their BL Link speakers. How many can he connect? Leo says he isn't sure there is a limit. The key was to crack using one device at once and they do it with time codes.