I have two Groundmaster City units. One, for signal grounding, is connected to unused rca plugs on my Pathos TT RR integrated, and Modwright Marantz SA8005 sacd player. It replaced a Gutwire Perfect Ground cable on the Pathos amp, which provided a subtle reduction in noise/increase in articulation and musicality. I tried to use a 2nd Gutwire grounding cable on the sacd player but it must have created a ground loop because I gut hum. Just comparing the Groundmaster City with the Gutwire cable on the amp, the Groundmaster unit is about 40% better. And connecting a Groundmaster City to both amp and player at the same time created no hum or other issues, and surprised me with the resulting improvement in sound quality. My system had no obvious noise or electronic artifacts to begin with, but with source and amp connected to the Groundmaster city the sound was noticeably more relaxed, natural, and articulate. My 2nd Groundmaster City is for chassis grounding. It will be connected to casework screws on my Bybee Stealth Power Purifier and Modwright PS 9.0 power supply, once I receive the cables I ordered for this purpose.