The newer versions of the MI Audio Crunchbox has a presence control that can be adjusted by an internal trimpot. Sure it's a great addition to a great sounding distortion pedal, but it's sure a bitch to adjust on the fly. And it gets worse when you have to rehearse on amp set-ups different from your own, on stage or in the studio.

The external pot mod is a common mod to solve this problem. And even if you have an old version of the CBX, we can add in the presence control too, no biggy!