"They should all operate independantly"
Depending on what this means, the answer is either very simple or a simple "no way".
They sell constant impedance switchboxes that will allow the use of speakers in several rooms at the same time. You could augment this with level controls in each room. Of course, the same thing would be playing in each room.
Now, if you mean each room should be able to play something different, well, that's a whole 'nuther ball game.