because of the nature of what you are doing, it will most likely require that all of the control components be of the same manufacturer. I know alpine makes a touch screen monitor that comes with a sub box that has an AI net connector and I guess basic preamp functions. So you could hook a CD changer, nav system, etc ... to it and control everything from the touch screen. I am sure most of the others (pioneer, kenwood, sony, etc ...) have or will have similiar systems.
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car stereo is my religion ... be prepared to be converted