DS18 HYDRO NXL-X850.4D 4-Channel Marine Waterproof Amplifier Class D Full-Range 200 x 4 RMS @ 4 Ohm 2400 Watts Peak DS18 designed the NXL-X850.4D for customers looking for a compact and waterproof amplifier with exceptional power output and prioritizes boosting sound. The NXL series impressive power output is supplemented by its outstanding efficiency, and its durability in harsh conditions makes it a favorite among customers in need of a waterproof amplifier to be the powerhouse of their system. The NXL-X850.4D comes in a 4-channel configuration making it great for powering more complicated active setups