SX-2100AO is an audio output unit of the matrix system and can be mounted in an EIA equipment rack (2U size). Multiple units can be decentralized in a whole system. It is equipped with eight audio outputs, and two inputs can be mixed and output. It is also equipped with eight control inputs, and eight control outputs. SX-2100AO receives audio signals from the audio input unit via digital transmission, but an analog audio input function (1 channel) enables simultaneous all-zone calls for use in emergency situations. Audio output levels are indicated on the level meters provided for each output channel. Volumes can be adjusted for each channel using the volume controls on the front panel or SX-2000 software. The volume controls can be locked. Any output channel can be monitored using the internal speaker. Two channels of local audio inputs with control inputs are provided as the dedicated audio inputs. Its functions include an amplifier switching function that automatically switches the power amplifier to the standby amplifier if the power amplifier fails, and a surveillance function that self-diagnoses the speaker lines. Equipped with two channels of interfaces for connecting to the emergency power supply units, making it possible to configure the system to operate during a power failure. One control IN/OUT interface allows the number of control inputs and outputs to be increased. The SX-2100AO has two power inputs and can support a dual-redundant power supply system.