PDX-5M is Alpine's 5-channel system-building amplifier, specially engineered for the marine environment. It embodies a compact chassis size, yet it produces powerful, precise sound. Built to withstand the harsh environment, the PDX-5M resists UV rays, saltwater, and fog. Revolutionary design incorporates improved feedback circuitry and power supply filtering system, plus a damping factor that is 350% better than Class A/B amps. A combination of Class D design and switch-mode digital amplification allow PDX amplifiers to stay efficient at all power levels. This produces less heat and eliminates the need for large heat sinks. RCA output and gold-plated RCA input connectors. Continuously adjustable gain control. Provides 75 watts RMS to 4 channels and 300 watts RMS to a subwoofer.