Treble and bass controls

Hi, I’ve had some luck getting my physical volume knob working, and now I’d like to add knobs for treble and bass. The case I’m using is from an old tube radio, and it originally had 4 knobs! Anyways, is there a way to issue an alsa command for bass or treble in a similar way that the volume knob works with mpd? Not looking for a guide here, just some pointers. Anyways, thanks in advance!

Umm. If you are wanting software bass and treble controls this may not be for you. Any alteration to the audio output would severely lower the sound quality. You might as well just use a smart phone which has audio player apps which no doubt would have EQs that can be enabled.