Audio system and processing method of storing and reproducing digital pulse width modulation signal

A digital audio system to store and reproduce a digital PWM signal and a method of processing an audio signal. The method includes; converting an audio source signal into a digital pulse width modulation (PWM) signal through a series of signal processing processes and storing the PWM signal in a separate storage medium, when an audio signal is reproduced, reading the digital PWM signal stored in the storage medium and decoding the signal into an analog PWM signal, and performing a power switching operation with the decoded analog PWM signal and extracting an audio signal.