Until a few years ago much Hi-Fi, AV and computer equipment used Class 2 electrical safety, which included an earth. As a result, often systems had multiple earths, leading to earth-loops with the result that often systems had hum and buzz.
As a result, many manufacturers have moved their equipment to what is called Class 3, which is “double-isolated” and has no earth. All Class 3 equipment contains both intentional (actual components) as well as unintentional (parasitic) capacitance between mains and ground.
As long as there is at least one earth in the system this is no issue, as all this noise will return to the earth via this single earth. If there is no earth whatsoever the results are unpredictable and can include hum and other noises picked up via various routes.
Adding a supplementary earth for audio use is highly likely to make the system completely silent hence we produced the Groundhog.
