There is disclosed a digital audio equalizer comprising an analog/digital (A/D) converter for converting an analog audio signal into a digital audio data, a digital interface receiver for demodulating the digital data that have been modulated into a digital audio interface format into the original audio data, a signal input select switch for selecting one of the outputs of the A/D converter and digital interface receiver, a digital signal processor for receiving the output of the signal input select switch to digitally process equalizing function, a microcomputer for controlling the digital signal processor, a key input circuit for controlling the operation of the microcomputer, a state display circuit for displaying the parameters of the equalizer, and a digital/analog (D/A) converter for converting the digital output signals of the digital signal processor into analog audio signals.