Garmin® JL Audio® Monoblock Car and Marine Subwoofer Amplifier 1 Channel 300W. With NexD™ technology, XDM amplifiers achieve total amplifier efficiencies exceeding 80%. This results in reduced energy use, making them much kinder to your electrical system. Innovative circuit design ensures the amplifier will never shut down due to thermal overload and keeps the music playing, even under the most demanding conditions. Choose from 3 options: auto signal sensing with +12-volt remote out; auto DC-offset sensing with +12-volt remote out; or conventional +12 volt turn-on lead. The all-aluminum, powder-coated housing inhibits corrosion, and a sealed security cover protects controls from the elements.