The 12VAC Brick™ is designed to function properly with an input power of 11-13VAC. The Brick will not operate from a DC voltage. A 2.1mm P5 style connector is used for the power input. If the input voltage is a grounded system, the center pin of the P5 is the power connection and the barrel is the ground side. All ProSeries units are shipped with a 12VAC, 600mA floating power supply that eliminates any ground loops through the power supply connection. The input for this product consists of a loop-thru input with two RCA/Terminal Block connectors. An audio signal with excessive DC component (or offset) will cause the VAC Brick to malfunction. The audio signal needs to be within -4V to +4V. The VAC Brick has four audio outputs consisting of RCA/Terminal Block connectors. Unused outputs do not need to be terminated for proper operation of the Brick.