FWIW the main purpose of the electrical service to earth connection is for lightning protection.
Kind of. That’s why the ground rods, but the reason there’s a ground wire in equipment is for short circuit protection, not surge.
It does nothing for the sound of an audio system.
I dont’ think this is proven, or even well investigated. If you wanted to show this, you’d have testing done with say, an elevated ground and measurements of noise on the ground wire in a home, and then also do some testing to see how well this noise can or cannot couple to audio systems.
In my mind there certainly are simple engineering explanations for how poor grounds (i.e. high resistance to the earth) cause noise to be shared in the home, and then capacitively (spelling? ) coupled to an audio signal. What’s sad is that these test would be easy for a lab to do, but I havent’ really seen any done.
Perhaps in Fremer’s case, the real need was to improve the ground farm and have a dedicated ground wire from his sub panel to it. Of course, the rest of the house would be bonded there as well. That would have been far less expensive than moving the service breaker outside, where it is subject to accelerated corrosion, and pulling a new sub panel from there.
I remain open to the possibility that good overall house grounding reduces noise in audio signals. I also think that even if it is proven, people will charge far too much for the solutions. :-)
BTW, while the house ground may be there