DS18 4 Ch Marine & Powersports Amplifier 1600 Watt Class D With Fuse & Holder. (1) DS18 Marine Amplifier NXL-X600.4D. (1) DS18 Marine Grade Fuse Holder. The NXL Marine Amplifier series is exactly what the outdoors lover will need for their boat or vehicle audio to brave the trails, enjoy the lake, or any situation that needs a strong versatile waterproof amplifier.