I asked myself this morning...Is there a way to turn off my External Master Volume (distortion) while I'm playing and get a clean signal. Basically a channel selector. I got the idea from Paul Marossy's "Solo-Pro" from www.DIYguitarist.com but changed it so that when the 3PDT switch is "on" the External master volume/distortion is activated and when the 3PDT is off the external master volume is bypassed for a clean signal with a volume control. With this little gizzmo I can use it to select between distortion and clean "channels" on my Ampeg V4. Be sure to connect all grounds!