Wow! That's a very nice job! Thank you very much for your answer. As you did, I'll add the second switch to the expression pedal. I see that you really modified the main board in order to hack up the 2 button switch and also to move the stomp button, so perhaps you know, more or less, how everything works. I've been thinking how the 4-button footswitch really works and perhaps you can help me out; I was wondering if the mode button (the one that you can select the tuner...) just selects "something" in the footswitch but not in the amp so you can, for example, select QA1 or stomp. This is, it doesn't send any signal to the amp, it just changes a logic state in the footswitch. If it works that way, it would mean that I could "easily" hack the pedal and I would be able create a 9-button footswitch (qa1, qa2, qa3, down, up, bank, stomp, mod, delay) by mapping every function of the 4-button footswitch. If the 4-button footswitch doesn't work as I mentioned, I think it would also be possible to do what I intend to, but it would too complex for my abilities.