I know this isn't a guitar forum ... but I'm hoping that some of you might have the answer to this: The lead guitarist in my band uses this amp: http://www.samedaymusic.com/product--LINSPIII120 Line 6 Spider III 120 watt amp. It doesn't sound terrible, but with only 2x10 speakers, it really has a hard time keeping up with the rest of the band (i run a full stack, rhythm guitarist has a mesa half stack and drummer hits hard as hell). Now, we've been pressuring the guitarist to upgrade his rig, but he's always broke. He won't have the cash any time soon to get the tube amp/ half stack we all want him to have. I was talking to a guy a few weeks ago who mentioned the possibility of re-wiring his amp to include an output that would allow an extension cabinet. It currently does not have such capabilities, as it only has a headphone out. Does anyone know where I could find a schematic or whatever it's called on doing this? I have a soldering iron and passable skills with it, so I'm hoping to do this for him so he could be running through a 4x12 cab vs. the 2x10s he currently is. Any help is much appreciated.