{TAIL ~ Audio/video device} having a volume control function for {HEAD ~ an external audio reproduction unit} by using volume control buttons of a remote controller and volume control method therefor 
{ TAIL ~ Audio / video device } having a volume control function for { HEAD ~ an external audio reproduction unit } by using volume control buttons of a remote controller and volume control method therefor
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH