Rockford Fosgate TM400X4AD Power Series Marine/Powersports 4-Channel Amplifier The Power Marine TM400X4ad 400 Watt 4-channel ultra-compact, amplifier is built on Rockford Fosgate's proprietary Class-AD technology, allowing the amplifier to produce more power with less current draw from the vehicle's charging system. Featuring Constant Power which results in up to 25% more output power and produces the same output at both 4-Ohm & 2-Ohm impedances. Flexible vehicle integration enabled through low-