The user clicks on a button that says “All DSP off” or something similar. This results in that all DSP chains on all tracks are temporarily disabled.
What is it good for? Well, for one thing it is useful when the composer just want to enter notes, building the structure of the song without burdening the CPU so much.
Ideally, this would work in the same way as the audio mute/solo features of the tracks, but additionally it would also give the option to mute/solo the DSP chain on specific tracks.
if this is done, make it a temporary over-ride, if it just changes the state of each dsp effect to off it could get irritating when you have idle effects in the chain, selectively re-enabling them the ones you want…