JL AUDIO CL-RLC 2-Channel Remote Level Hi-Low Amp Control and Line DriverJL AUDIO CL RLC 2 Channel Remote Level Hi Low Amp Control and Line Driver Fully Active, 2 Channel Remote Level Control and Line Driver with Pass Through Outputs For use as a subwoofer level control of a full range volume control Top quality active circuitry Minimizes (if not eliminates) the chance of having unwanted noise The control knob sends the volume level signal to the preamp circuit Control the subwoofer level or the full range speakers volume