TT on Symposium Super Segue - slate or maple underneath?

It’s the opposite. 

The seismic energy is not totally eliminated by devices since they are mechanical filters. So, cones are desired to prevent energy from being stored in the system, whatever that system is. Does the Symposium deal with seismic vibration? Maybe it does, but they don’t seem to address seismic vibration, so who knows? It should, since seismic vibrations are worse for the sound than induced energy.  Seismic vibration in the range 8-12 Hz excite the Fn of the tonearm, cartridge and platter.  In any case, what is required for best results is a comprehensive program of mass-on-spring vibration isolation AND energy dissipation/damping.

It’s a longish story how to optimally place a turntable on an isolation stand. To make a long story short, the component on the iso stand should be placed on very hard cones AND the stand or anything under the stand should also be placed on very hard cones. This set-up strategy allows for minimum upward 🔝 transmission of “seismic type” vibration AND maximum downward transmission of any vibration on the stand itself, which can arise from the turntable motor, acoustic waves, etc. what you want to minimize is stored energy in the iso system.