An amplifier controller for controlling a plurality of amplifiers connected therewith is provided. Each of said amplifiers is provided with one or more audio output channels. The amplifier controller operates in two modes of solo mode and normal mode. When the solo mode is initiated, the amplifier controller instructs all of the amplifiers to turn off output of all audio output channels provided in the amplifiers, and only in the solo mode, according to selection of an output channel for which solo output is to be performed, the amplifier controller instructs the amplifier provided with the selected channel to turn on output of the channel, and instructs each of the amplifiers provided with an audio output channel other than the selected channel to turn off output of the audio output channel.