I'm pretty sure Garcia did this somehow. If you had an additional knob on your guitar that could turn your OD pedal's gain/drive from light to heavy. To be able to control a pedal like a Timmy that can do the whole range from light gain to almost fuzz territory, would eliminate the need to have 2 or 3 diff OD pedals on your board. I guess the eq would simultaneously need to be adjusted on a Timmy, so maybe that's not the best example. I had a Sunface that you can control with your vol knob, but I am talking more about control drive without having to increase the volume significantly. Anyone know if there is a way?