i would wager that high quality decoupling of those speakers in Mr. Ludwig's studio would outperform the grounding to the bedrock. assuming, of course, that the decouplers sat on the bedrock.
the bedrock has it's own noise floor too. certainly less than the Studio building but it's there none-the-less.
another way to look at this would be how would an electron microscope be spec'd ideally to be installed in that spot. no way would it sit on the bedrock; you could never get the visual resolution you needed. you would need some sort of isolation. this isolation device would work best with the most solid footing, but it would be essential for optimal performance.
http://www.herzan.com/resources/tutorials.html
the 575 pound speakers in my room sit on 6" of concrete over 'Glacier Till'; which is the rock and dirt compressed from a receeding glacier. i'm on the side of a mountain far away from any main road or highway. so almost zero environmental energy. pretty solid stuff. yet the decoupling footers made a huge positive difference.