I just picked up a Tone Hammer 500. I have two 1x15 cabinets, each 4 ohms, so I can't run the TH500 with both cabs. I have a Walkabout head, so I tried connecting the TH500 to the Walkabout's power section by running a 1/4" instrument cable from the TH's send to the Walkabout's return. I...