has anyone else tried Lloyd Walkers latest tweak

IMO the only way the crystal as it is used on the cartridge could operate by absorbing or dissipating RFI/EMI is if it acted like a magnet for RFI/EMI, pulling in the offending electromagnetic fields like a black hole pulling in matter beyond the event horizon. If the crystal did not pull in RFI/EMI then wouldn't it be safe to assume the electromagnetic fields would still be there? It makes much more sense that the crystal absorbs or dissipates mechanical vibration, inasmuch as even low levels of vibration on the cartridge body could be audible considering the sensitivity of modern phono cartridges. Of course, we don't actually know what the Walker black diamond is made of. I trust it's not really a black diamond.

Just as a side note, the crystal in the Shakti Stone is part of an electrical circuit, albeit a passive one.

re: The Shakti- Yes; that it is passive, absorbs RFI/EMI(purportedly)) and is not grounded, was my point.

For electro-magnetic waves to be changed to audio signals(within a detector/crystal), they must be, "absorbed." The only thing a crystal needs to do so, is an antenna. Perhaps, in the case of the wavelengths that the Walker deals with, the size or shape of the crystal obviates that need( as I mentioned earlier). Just trying to present a plausible possibility, for Mr L.