The preamp is to amplify the audio signal to the input range acceptable to the power amp. It has the characteristics of selecting the required audio source signal and amplifying it to the rated level and beautifying the sound. The role of the preamp: Select the required audio source signal and send it to the rear stage, and at the same time close other audio source channels, and amplify the audio source signal to the rated level to achieve high-fidelity sound quality. The difference between an audio power amplifier and a preamplifier The preamp is to amplify the audio signal to the input range that the power amplifier can accept, and the audio power amplifier is to generate the maximum power output to drive a certain load amplifier under the specified distortion rate conditions. The preamp is an audio processing device before the input audio power amplifier; the amp controls the power of the sound, and the preamplifier controls the audio range.