Power amp in

An amplifier that is designed to drive loudspeakers or other relatively low impedance loads. Usually combines voltage and current amplification. May be integrated with the preamp (see below)

An amplifier that has higher-power output capability than a preamp and is designed to drive one or more loudspeakers. Generally contained with the preamp in self-contained or piggyback amps, but also available as a separate unit in some cases.

See Amplifier.

a device that increases the power of an audio signal by matching the input to the output of a regulated power supply. In live sound, power amps are used to amplify the signal after processing to power the speakers