I have not thought much about the actual mechanics and physics of turntables and arms but some of what I read does not make much sense to me. Perhaps someone can help me understand better.
Folks talk about "draining" energy to the earth or some other place of stability as if it somehow removes the effect. This does not make sense to me. If a tone arm resonates at some frequency it seems to me that it must be moving. That movement will eventually be damped by some mass, i.e. the movement will become undetectable. The resonance will if no longer being excited die out as the energy is dissipated as heat energy raising the temperature of the resonating part.
The damage from an audible perspective would seem to me to come from the movement. For the cartridge to reproduce what is in the groove it needs to be absolutely fixed relative to the groove. If it moves relative to the groove then that movement becomes part of the electrical signal as there is no way for the cartridge motor to know if the cartridge is moving or the cantilever is moving.
What I think Bruce is saying with his measurement technique is that if you can sense movement in the headshell of a tone arm, which is what you are doing by placing another stylus / arm on the headshell as it plays a record, that movement has to be counterproductive to the faith-full reproduction of the information in the groove.
