Folkfreak wrote,
"others with more knowldge of springs (Geoff?) may comment on whether the setup transmits higher frequencies, it may."
The springs are simply part of the mass/spring iso system. Analogous to seismic vibration isolation, isolating the system from the vibrational energy of the speakers (cabinets) is accomplished by absorbing the energy via the mass/spring system, where it’s converted to work and heat. The mass/spring system would thus have to move somewhat during the whole isolation process.