So my '89 Bose head unit has a CD player input (without changer controls). I don't have it in front of me now, but the pin-out had connections for: left, right, on, off, and maybe something else (it was a DIN plug with 5-6 pins). Has anyone studied the operation for this input? My guess is that the "on" signal goes from the head unit to the player to tell it to turn on, while the "off" signal goes from the player to the head unit to tell it to shut off the radio or tape and switch over to the player input. Can someone confirm this, and also which voltages do what? (Should the "off" signal be +12V to switch over to the player, or should it be ground?)