Yes, you will need an amp for a powered subwoofer. In most cases, unless your car or boat system already has a built-in amplifier specifically designed to power a subwoofer, you will need to find a separate amplifier to connect to your powered subwoofer. The powered subwoofer itself is designed to reproduce low-frequency sounds and enhance the bass in your audio system, but it still requires an external amplifier to provide it with the necessary power to function properly. This amplifier will help drive the subwoofer and ensure that it delivers the deep and powerful bass you desire. So, to fully enjoy the benefits of your powered subwoofer, make sure to invest in a compatible amplifier to provide it with the power it needs.