The advanced protection circuitry guards against short circuit and open circuit, and also protects against ultrasonic and RF interference. A high current power supply increases reliability and performance. Other features include center-detented gain controls, input peak limiter, selectable high pass filter, and fast recovery to ensure low distortion. The variable speed fans effectively cool the amp and protect against overheating. Input is through XLR or 1/4" connectors, while you can use Speakon-type or binding post connectors for output. Phonic XP Power Amplifiers are specially designed for professionals who value high power, audio clarity, reliability and lasting performance.