JL AUDIO XDM300/1JL AUDIO Monoblock Class D Car Marine Subwoofer Amplifier, 300 W x 1 @ 2 200 W x 1 @ 4 14. 4V This little monoblock powerhouse employs our high speed NexD switching design to achieve unprecedented efficiency and amazing power output for its size. It is small enough to fit in most tight space applications, including small boats, pickups, motorcycles and UTVs (in a weather tight compartment). Designed for car or boat installations, the XDM300 1 is built