I've posted this question and received a lot of feedback over at Audiogon, but I'm not really satisfied with the answers:
In a nutshell I'm getting woofer movement on my sub and main speakers whent he stylus hits the groove - enev in the lead in/out grooves before music is playing. I have very good rack, shelf and TT isolation. I think it is subsonics and am looking for a better way of dealing with this, short of buying/building a subsonic filter. I can live with it, mostly by turning off the sub, but would rather hear optioins on how else to deal with it.
Recently someone suggested adding some additional weight at the headshell, then rebalancing the tracing force back to 2g to see if this adjusts the resonance of the tonearm and reduces the cone movement.
Any other thoughts?