To provide a surround amplifier system that can make suitable surround reproduction for a program, whenever programs are changed.

A tuner circuit outputs audio signals contained in broadcast signals to an audio-processing circuit and a radio data system related signal (RDS signal), contained in the broadcast signals to a microcomputer. The microcomputer stores correspondence relation between PTY codes indicating the kinds of programs and surround modes and designates a processing mode specified by the corresponding surround mode to the audio processing circuit, by detecting and discriminating the PTY code contained in the RDS signal. The audio processing circuit performs surround processing on the audio signals in the designated processing mode. A user can set the correspondence relation between the PTY codes and surround modes from an operating section. The microcomputer detects and discriminates an M/S flag, which indicates whether corresponding audio signals are mainly for music or for conversations, and when the flag indicates that the audio signals are mainly for conversations, designates a processing mode which contains no surround processing, regardless of the stored contents.