What is the role of a power amplifier in an audio system?

A power amplifier serves a crucial function in an audio system by increasing the amplitude of low-level audio signals so that they can drive loudspeakers effectively. Low-level audio signals, such as those from a microphone or a line-level source, are often insufficient to effectively drive loudspeakers, which require more power to produce sound at higher volumes. The power amplifier takes these weak signals and amplifies them to a level that can drive the speakers, ensuring that the sound produced is loud enough for listening.

The other options refer to different functions in an audio system. Converting digital signals to analog is the role of a digital-to-analog converter (DAC), not a power amplifier. Filtering out unwanted noise from audio signals typically involves the use of filters, which are not the primary function of a power amplifier. Adjusting equalization settings relates to tone control and audio processing, which again falls outside the specific job of a power amplifier.