GigRig Humdinger for sale....I used to use two of these with a GigRig pro-14 for switching channels on two amps at the same time, one of many things it can be used for.They are £111 new and I am selling at less than half that..... I have not used eBay for a while but please check my excellent feedback... Here is some more technical info from the website.... Thanks If you use 2 amps, mains powered effects,or need to drive long cables, the HumDinger is essential. The Humdinger was designed to eliminate earth loops in audio equipment by isolating the second output with a high quality audio transformer. 1. The Main output is buffered using our custom designed 1:1 class A buffer design guaranteed not to mess with your tone. 2. The Isolated output uses a high quality audio transformer to the best signal possible. 3. The isolated output also features a PHASE switch, so you can get rid of any phase problems between two amplifiers. 4. Both outputs will drive long lengths of cable so you don't need to worry about the distance between your pedal board and your amp. 5. It's impossibly small and will fit on even the smallest of pedal boards. Earth loops are a common complaint. As soon as the ground on your gear has more than one main route to earth, you have the potential for an earth loop. The best and safest way to get rid of an earth loop is to isolate the ground that is causing the hum. Using the HumDinger to get rid of earth loops is easy. If you use 2 amps all you need to do is stick the HumDinger at the end of your effects chain. Your main (buffered) output goes to one amp, and the isolated output goes to the other. Your earth is consistent through the main output but isolated through the isolated output. Using a mains powered effects pedal, simply place the HumDinger in the chain after the mains powered effect. The Mains powered effect is your main ground and the ground from the amp is isolated.