Music. Defined. Our mobile automotive amplifiers, subwoofers, and speakers come in a wide range of high-quality affordable to premium options. MB Quart is second to none. Designed for off-road vehicles, trails, and the water, Nautic Marine and Powersports products feature Bluetooth controllers, AM/FM Bluetooth source units, compact and full-size marine amplifiers with high power, high-volume compression horns, and heavy-bass subwoofers.