Do you want to loose the touch sensitivity and not hear the WAH filter modulate? Or do you actually hear a completely bypassed sound? Setting the SENS to 0 on the speed knob will stop the movement of the filter, but will not bypass the filtering. The WAH is a bandpass filter that starts at BASE on the xknob and moves by the DEPTH amount. So, even if you don't move it, it's still a bandpass at BASE. The only way to bypass the effect completely is with the footswitch.
