Audio power amplifier refers to the most basic equipment in audio system. Its task is to amplify the weak electrical signal from the signal source (from the mixer in the professional sound system) and drive the speaker to make sound. Short for speaker, commonly known as "amplifier". The function of the audio power amplifier is to classify "THD+N" from the sound source into categories: None published in: 2003-1-131:19: 02 In the article introducing the audio power amplifier, THD+N is