In response to JK above: Notice on the star grounded rig photo there are green wires all going to a terminal strip - that's the star point, and its connected to the main AC ground. Ground was lifted from all power cables and chassis and then re-connected to the star point. "Is star grounding the CURE for all grounding issues?" Yes - it is a comprehensive solution. No - it's not the "end all, be all" solution. After doing a few star-grounded rigs I abandoned the practice and started applying the concept using the rack rail as the common ground. Start with all AC plugs grounded, chassis grounded, and then lift AC and audio cables as needed. I'm not a fan of trying to isolate all units from the rack rail - especially if the rig will be moving (tour, gig, etc.). See above. I agree with Lonnie on this topic. Multiple preamp sources I feed two preamps (amps) with a Jensen JT11P-1 isolation transformer with RC network. I mount the trans in a hammond box or the rack interface and connect it in parallel with the grounded "through" signal. The guitar only sees one "load" and sounds and feels like normal. The output of both preamps go to a loop - Amp A goes to the input of the loop, Amp B hits the return. The result is both preamps are fed input and you have a programmable A/B "preamp chooser" via the loop. Clear as mud?