Tek, the best thing to do is measure the AC potential with any new piece of gear as just need a cheap multimeter, decent earth ground and a cheater plug....Go to www.boundforsound.com and print the article for checking this under "tweak of the week"....The problem manifests itself in poor imaging as all the gear is hooked togther via interconnects and just one piece with high AC potential will mess up the whole system....If the AC is backwards you can attack it two ways; get inside the unit and swap line and neutral or order a cord which will fix the problem....Lots of folks don't like playing around inside their gear so I sell quite a few reversed polarity power cords....This is the sort of thing dealers used to check before most of them just started selling sealed boxes......