PURPOSE: To allow one channel processor to process a digital stereo audio multiplex signal as well as a monaural signal.

CONSTITUTION: When a television broadcast signal fed to an input terminal 30 includes a video signal and an audio signal, the signal is fed to a distributer 42 through a changeover switch 40, the video signal is extracted and amplified to be a 1st level signal at an amplifier 46. The other distribution output of the distributer 42 is fed to a band pass filter 50, from which an analog audio signal is extracted and amplified to be a 2nd level signal at an amplifier 52. Output signals from the amplifiers 46, 52 are mixed by a mixer 48 and the mixed signal is fed to an output terminal 62 via a changeover switch 56. When the television broadcast signal includes also a digital audio signal, the video signal, the audio signal and a digital intermediate frequency signal through the band pass filter 44 by way of the changeover switches 40,56 are fed to an output terminal 60.