No cables were available to take the 12 volts from the Din 5 #3 pin out of my DC-1 to connect to the 7500. Steve could not find any either. So I went to Radio Shack and got a MIDI cable and a 3.5 mm mono cable. It turns out that a MIDI cable has 5 pin DINs ends. I cut both cables in half. I used an ohm meter to find out which pin was switched pin (#3) and ground (#1 or #2). I connected the cables and voila my amp is now switched by DC-1.
Cost =$15 for the cables.
Joel