The BAL2S input module shall be a stereo, high-impedance, electronically-balanced input module. It shall be mutable by higher priority modules and shall feature an internal PCB jumper to enable or disable muting from the priority bus system. It shall have a continuously variable ducking control that will enable attenuation of the input signal from a minimum of 10 dB to a maximum of 48 dB relative to the normal unmuted condition. The module shall have a rapid mute when the mute function is activated and a gradual fade back from mute when the mute control is deactivated. Gain shall be switch selectable per channel and shall be 0 dB or +18 dB.