Ground control to major components
The optimum configuration for each system is one ground/earth for the whole system. If a system has multiple grounds/earths, then it often creates unwanted ground loops. These systems will then have an annoying low-frequency hum (emitted from the speakers).
Current solutions either jeopardise both safety and EMI shielding (e.g. cheater plug), or EMI shielding. The GND Defender is the correct way, intelligently detects a ground loop and will optimize the ground for that component. Ground control to major components.
A Brace of Buzz Busters from iFi - The GND Defender and DC Blocker by Bruce Kinch @ posi+ive-feedback