An A/V amplifier in which a multi-channel reproduction mode and a 2-channel stereo reproduction mode can be selectively switched, comprising: a decoder that decodes a multi-channel encoded input signal and outputs a multi-channel signal in the multi-channel reproduction mode, or outputs a 2-channel stereo input signal as it is in the 2-channel stereo reproduction mode; a plurality of PWM amplifiers (104A - 104D) for amplifying an output signal of said decoder, corresponding in number to the number of channels in the multi-channel reproduction mode; a plurality of terminals (105A - 105D) connected to a plurality of speakers (106L, 106R) in one-to-one correspondence, for transmitting outputs of said plurality of amplifiers (104A - 104D) to said speakers (106L, 106R); a channel selecting unit for selecting the multi-channel reproduction mode or the 2-channel stereo reproduction mode; and a switching circuit (108, S1 - S14) for switching the connective relationship between said decoder and said plurality of amplifiers (104A - 104D), and between said plurality of amplifiers (104A - 104D) and said plurality of terminals (105A - 105D) according to the mode selection; wherein when said channel selecting unit selects the multi-channel reproduction mode, said switching circuit (108, S1 - S14) allows the output signal for each channel in said decoder to be sent to said plurality of terminals (105A - 105D) via respective one of said plurality of amplifiers (104A - 104D); and when said channel selecting unit selects the 2-channel stereo reproduction mode, said switching circuit (108, S1 - S14) allows at least two amplifiers (104A - 104D) among said plurality of amplifiers (104A - 104D) to be connected in parallel between output terminals for each of channels L and R of said decoder and said terminals (105A, 105C) corresponding to each of the channels L and R, and allows the timing of noise in output signals of the respective one of said plurality of amplifiers (104A - 104D) to be varied. a decoder that decodes a multi-channel encoded input signal and outputs a multi-channel signal in the multi-channel reproduction mode, or outputs a 2-channel stereo input signal as it is in the 2-channel stereo reproduction mode; a plurality of PWM amplifiers (104A - 104D) for amplifying an output signal of said decoder, corresponding in number to the number of channels in the multi-channel reproduction mode; a plurality of terminals (105A - 105D) connected to a plurality of speakers (106L, 106R) in one-to-one correspondence, for transmitting outputs of said plurality of amplifiers (104A - 104D) to said speakers (106L, 106R); a channel selecting unit for selecting the multi-channel reproduction mode or the 2-channel stereo reproduction mode; and a switching circuit (108, S1 - S14) for switching the connective relationship between said decoder and said plurality of amplifiers (104A - 104D), and between said plurality of amplifiers (104A - 104D) and said plurality of terminals (105A - 105D) according to the mode selection; wherein when said channel selecting unit selects the multi-channel reproduction mode, said switching circuit (108, S1 - S14) allows the output signal for each channel in said decoder to be sent to said plurality of terminals (105A - 105D) via respective one of said plurality of amplifiers (104A - 104D); and when said channel selecting unit selects the 2-channel stereo reproduction mode, said switching circuit (108, S1 - S14) allows at least two amplifiers (104A - 104D) among said plurality of amplifiers (104A - 104D) to be connected in parallel between output terminals for each of channels L and R of said decoder and said terminals (105A, 105C) corresponding to each of the channels L and R, and allows the timing of noise in output signals of the respective one of said plurality of amplifiers (104A - 104D) to be varied.