I"m going to go out on a limb here and say the MCU does not support multiple audio paths. I don't think we'll ever see Bluetooth headphones in the back, which kinda defeats the entire point. I say this because when you have the horn sound changes, and you press the horn. For a split second the horn sound plays through the car speakers and switches to the outside speaker and turns the audio off in the car. This tells me its using the same path for everything.