High efficiency and reliability are due to switched-mode power supplies combined with dual-channel Class D amplifier technology. A temperature-controlled fan keeps all parts in the correct operating temperature range, avoiding excessive noise. An integrated multi-purpose protection circuit protects against direct current, short circuits, overheating, overload and limits the signal if necessary. Input connections are made on balanced XLR connectors and XLR return output connectors allow connection to other amplifiers. At the same time, each channel has a high-pass filter switch (400 Hz) and a gain control potentiometer. The output connections are made via reliable busbars and the entire unit is housed in a rugged case taking up two units of 19" rack space.