The control unit controls {TAIL ~ the audio signal processing unit} to adjust the volume control values for {HEAD ~ the audio output port} by the volume control buttons when the external audio reproduction unit is plugged in the audio output port 
The control unit controls { TAIL ~ the audio signal processing unit } to adjust the volume control values for { HEAD ~ the audio output port } by the volume control buttons when the external audio reproduction unit is plugged in the audio output port
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH