The trouble is, the sound system is inevitably connected to the rest of the car. For example, in most cars the volume automatically increases with vehicle speed to compensate for increased road noise.
These connections could be physically 'one-way' but in practice most modules are simply wired in parallel on a CAN bus and something like the radio would be set up to
send data to the car's CAN bus (for diagnostic purposes at least).
These connections could be physically 'one-way' but in practice most modules are simply wired in parallel on a CAN bus and something like the radio would be set up to send data to the car's CAN bus (for diagnostic purposes at least).