We updated ours, using model IM-3303 and the original wiring in the house. Works like a charm. You will need to use a new rough-in, because it holds the new transformer. I've been replacing the speakers as I get to them, one at a time. Not necessary, but they sound better.

We bought ours thru a local electrical supply house. I've put a link below that has some good information.

Here is a link that might be useful: updating a 3003

I just saw the Russound has a new intercom system, check it out on their website. When I go to put in whole house audio, I might use this at that time.

is your old unit 3003 for sale