It's more than that. Besides having an interface which converts CAN signals to analogue signal for the Pahtbox, you will also need to have an audio in on the head unit which allows using the head unit controls. The TV tuner and the US SAT receiver are the only devices controlled via CAN. The SAT option is only available in the US software and the TV screen turns blank when in motion. Until Audi offers more CAN enabled audio devies, adding non-OEM audio devices may be more difficult than expected. Leaves the question why it's so diffcult for Audi to develop a USB (or similar) CAN controlled audio in with hooks like the US SAT receiver.