Kicker DX500.1 Mono Subwoofer Amplifier, 500 Watts RMS x 1 at 2 ohms FIT (Fail-Safe Integration Technology) utilizes differential inputs to reject noise and electrical interference for the quietest operation possible and ultimate audio clarity Muting circuit cancels out unwanted noise Balanced differential inputs for noise elimination and factory-radio compatibility Dual input sensitivity differential RCA inputs which receive high or low level signals Speaker-level input compatible (switchable) through RCA connection, Kicker 09ZISL required and sold separately