I did exactly what Markus said. I had my complimentary amps on the same patch number. You can change presets with the push of one button. I used my ground control pro and had one midi cable going to the midi in of the first eleven rack and then another cable going from the out/thru to the second. The only thing you can't do with that setup is change effects individually between the two racks, as hitting the button programmed for delay will turn on or off the delay on both presets. Does sound amazing when done right. I used a signal splitter made by radial to split my signal to go to both amps.