@michaellent Please read my previous post. If the floor is concrete laid on the ground the mass of the Earth will absorb all forces from the speaker via the spikes. The forces can only bounce back to the speaker if the Earth is moved by those forces. But as I say the Earth will not be moved because of the huge mass discrepancy between it and the speaker. It will simply absorb the forces.
Flat dwellers in big modern blocks with concrete frames standing on piles driven into the Earth and concrete floors fixed to the concrete frames will obtain similar benefit.
Putting the speakers on flexible supports that allow the speakers to move will cause far more distortion. Max has made a lot of money by convincing people otherwise. Although those with suspended wooden floors are his legitimate customers and there are plenty of them.