Originally Posted by bassmanbigs
there is a SPDT slider switch on the bottom already. I want to reroute it to a SPDT Footswitch. But it wont fit on the top.
Can you get a picture of the wiring?
From what I see online, I would assume that the two terminals of the jack go to the common terminals of both switches, and then the normally-open terminal of the main switch goes to one throw of the polarity switch, and the normally-closed terminal of the main switch goes to the other throw of the polarity switch. If that is the case, all you have to do is replace the attached cable with balanced, two conductor cable, and put a TRS jack on the end. Then the two sleeve terminals of the external footswitch box can be connected together (Make sure you wire the common terminal on the M-Audio SP-2 to the sleeve.), and the new footswitch can select either the tip or ring from the M-Audio SP-2, to go to the tip terminal of the jack going to the keyboard.