I've had an RGC-24 grounding device in my system for several years. When I got it I felt it made a difference and used it via an unused RCA on the back of an Aesthetix pre-amp. I recently changed amps to an Analog Domain Int and reinstalled the ground to it's ground point, should A/B but haven't.
The dealer lent me a Schumann Generator for a few weeks but I didn't notice any benefit so returned it
The dealer lent me a Schumann Generator for a few weeks but I didn't notice any benefit so returned it