Didn’t know that good house grounding for audio was a thing until I read about Fremer’s grounding odyssey.
FWIW, Fremer’s existing Earth Grounding was not his problem with the degraded sound he was hearing from his audio system. The problem was the insertion of the new ATS switch into the normal AC power system that feed his audio system equipment.
( New ATS, Automatic Transfer Switch, for his new whole house back up generator power system for his home.)
I would imagine a whole new electrical service helped improved the sound from his audio system even more.
The elaborate low earth to rod resistance earth connection, (deep driven into the earth ground rod), does nothing for the sound of his audio system. The electrical service earth connection, grounding electrode, is mainly for lightning protection. The Earth does not possess some magical mystical power that will suck nasty noise from an audio system.