Apparently I don't. I got a GK MB200 and a Hartke 210XL cab. I got a cable that I thought would work, but upon looking at the amp I'm not sure. It's a speaker cable, not an instrument cable. It's got 1/4 connections. Would I go from the line out on my amp? Or do I go from the one that says speaker? I would need a different cable for that which I don't have.