@saulh no it is not a suspension at all. The magnetic field is compressed by the weight of the platter until it is almost as stiff as a solid thrust mechanism not to mention that the platter is still located by a solid spindle.
@clearthinker, vibrations can pass through springs but only below the resonance frequency of the suspension. Springs are mechanical low pass filters. The suspension on my Sota is set at 2 Hz with a very high Q so by 8 Hz everything is blocked. No mechanical vibration above 8 Hz gets to the sub chassis. Since the sub chassis is entirely enclosed by the plinth and dust cover much less airborne vibration gets to it.
MASS DOES NOTHING TO ISOLATE A TURNTABLE FROM MECHANICAL VIBRATION. I will say this until I am blue in the face. It does help with airborne vibration but not mechanical vibration. This is the vibration that is passed on to the turntable through whatever it is sitting on. Some people have called it "room Rumble" as it occurs at very low frequencies right about where tonearm resonance hits which only serves to amplify the rumble. Foot fall problems are "room rumble" generated by walking. Room Rumble is generated by anything and everything that is going on in the environment from the cement truck running down the street to various house mechanicals turning themselves on and off. Mass does not protect you from this and in the minds of some (Rega) can make things worse. Sound waves travel through the ground just like through air. When they get severe enough you get an earthquake. There is a constant din going on in the background it is just below the level and frequency our own senses can detect but not the cartridge, it feels everything. That is what it is designed to do.
So, clearthinker, throw away your Kuzma Stabi XL DC AIR and get yourself a real turntable like a Sota, Basis, Avid or SME and enjoy listening to music without rumble. It will be an entirely new experience for you.