Paul Cochrane TimVerified

From the post

A few people have asked for this so thought I'd add it. If you want to include the loop it's a pretty simple affair. Volume 2 goes to the tip of a switched socket (Send), and the normally closed contact from the tip goes to the main stomp switch board output lug, and also the tip of a second normal mono socket (Return). So when no cable is in the Send socket the signal is being passed directly to the main bypass stomp switch. When a cable is inserted into the Send socket, the contact is broken and so all the signal passes through the Send, back through a return cable to the main stomp. A 510K resistor is also soldered between the tip and shield of the Return socket to act as a pulldown resistor for the output of whatever is in the loop.

I think if I was going to build this I'd probably add a third stomp and have the loop switchable on the fly to make it a little more versatile. Then you wouldn't have to bother with a switched socket and could use conventional true bypass wiring of the additional stomp to bring the loop in and out of circuit.