Digital audio amplifier and digital audio amplifying method therefor

A digital audio signal amplifier and a digital audio signal amplifying method provide safety and power efficiency by integrating a switching mode power supply and a digital audio amplifier into an apparatus. The digital audio amplifier includes a pulse modulation unit generate a pulse modulated audio signal by pulse-modulating an input audio signal, a switching unit to switch a DC voltage based on the pulse modulated audio signal, an insulation transformer to transform the output of the switching unit and to output the result of the transforming, and a low-pass filter to obtain an audio signal corresponding to the input audio signal by low-pass filtering the output of the insulation transformer, and to output the output audio signal. By integrating a switching mode power supply and a digital audio amplifier into an apparatus, the digital audio amplifier satisfies the insulation requirement and at the same time increases power efficiency.