Hi Josh:
The SSVC6D uses a Transformer type Impedance matching internal Volume Control for each zone. There are jumper settings that can be changed for each internal VC depending upon you application. There are not Resistor based volume controls that have Impedance Matching capability. Our ISS and DSM series Speaker Selectors feature internal Protection using sandstone resistors. But it cuts the power handling capability in half when you enable the internal protection; 140 watts without and only 70 watts with protection enabled. Typically we recommend using impedance Matching Volume Controls to handle the protection. In those cases we instruct you to make sure the internal protection of the switcher is disabled (the off position).
TL/4198