It is necessary when you want to control the volume in a single zone/room, separated from the others. Provided with triple screw terminal, it inserts between signal distribution line and the speakers of a given zone. It is also provided with a switch which opens when the volume control is rotated until zero. The switch, with separated terminals, can be used to stop the power to the amplified speakers when the volume is zero. It occupies 1 unit in civil series.
