If I’m understanding, you’d like a use the c buffer board, but have a toggle sw that bypasses or activates the buffer, independent of the main circuit (od or boost) in the pedal. Correct?
Unfortunately I think it will be hard to do this with the c buffer board. This pcb was designed to be an always on buffer, regardless of the stomp switch. Because the buffer circuit it connects directly to the stomp switch, you can't isolate it. You could, if you wanted, easily throw a toggle or stomp on there that bypasses the whole pedal (buffer and main circuit), so you’d have true bypass if needed, but that might not be the most practical.
