The P350 is the companion amplifier to Phase Technology custom in-wall subwoofer systems but its use is not limited to only subwoofer applications. It also has the flexibility of operation as a full range high current, high performance, mono-block audio power amplifier. <p>The P350 is designed to be used with SoundTube, SolidDrive, Rockustics, and Phase Technology. When using with outdoor products, the amp should be located indoors or in a weather-proof encasing.