Interesting.
I can't really help you since my whole-house speaker setup already was here when I moved in. However, FWIW, my whole house system which is simply speakers all around the house hooked up to (I believe) impedance balanced volume switches, all connected to a multi-zone speaker selection hub, which in turn is hooked up to a standard audio receiver.
The receiver is hooked up to an Airport Express, which gets music from iTunes on my iMac. All is controlled by my iPhone. Note that I found wireless 802.11g with the Airport Express unreliable, so I actually use: iMac --> Ethernet --> powerline networking --> Ethernet --> Airport Express. (There was no existing CAT5 for this purpose, so I had to improvise.)
I can hook up other audio sources to the receiver too, but obviously I have no way of controlling them from the iPhone.
However, I assume your house's walls are already drywalled. If not, you can add all the wiring easily. If so, then no dice.