My amplifier had been cursing me for several years with an incredibly annoying buzzing sound. It got so bad that I disconnected the rear channels so that the problem was isolated to the main speakers at the far front of the room. I'd done all the various diagnostics on the electrical wiring in the house, but still no joy, the buzz continued. Finally, in a fit of desperation I found this little device on line and bought it. It's amazing, after putting this between the amplifier and the plug the buzz went away. It's so good I checked twice that it didn't just lift the ground, but sure enough it filters the noise away. A complete joy! If you have an intransigent ground loop driving you insane, definitely get one of these. It's cheap compared to all the time trying to find the darn ground loop (and in my case failing).