An apparatus is provided for remotely monitoring a plurality of amplifiers on a display device. The amplifiers are provided to process audio signals and directly or indirectly connected to a network. In the apparatus, a collecting section collects a group code from each of the amplifiers through the network. The group code is allocated to each amplifier according to a grouping system for grouping the plurality of the amplifiers. A display control section displays a tree diagram of the amplifiers according to the collected group codes on the display device as a graphical representation of the grouping system.