Maxxsonics MX-4 Add-A-Sub High-to-Low Level Converter Add-A-Sub High-to-Low Level Converter Converts and filters high-level factory speaker wires into ultra-clean unbalanced (RCA) low-level signals to an aftermarket amplifier High Level Inputs: Accepts all types of high-level input signals including floating ground type, low and high voltage speaker wires OEM high-level input voltages are adjustable from 4 volts to 40 volts Unbalanced line outputs are adjustable to the aftermarket amplifier from 4 volts to 9 volts