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Power Amplifier
Definition
A power amplifier (power amp) takes a line-level signal and raises it to speaker level: enough voltage and current to move speaker drivers. Typical power amps do not switch sources or control volume. They amplify one input.
Rated output is usually continuous (RMS) watts per channel into 8Ω and 4Ω, at a stated THD.
In a stereo system
A power amp needs a preamplifier (or an integrated amp used as a preamp) in front of it. Pair it with passive speakers. Powered speakers already have this stage inside the cabinet.
Match the amp's minimum load rating to speaker impedance, and match power to sensitivity and room size. Damping factor describes how firmly the amp controls cone motion after a transient.
An integrated amplifier is a preamp and power amp in one chassis.
