What we are looking for here is the stabilization of the speaker. Ideally you don't want the speaker to move around as it will counter the movement of the cone (domes, ribbons) creating the output.
If you have a carpeted concrete floor then spike it straight to the floor. Problem solved. The concrete floor doesn't move.
If you have a lossy floor (suspended or wooden floor), then it helps to use a damper.
The reason to use a damper isn't because there is energy being transferred from the speaker cabinet to the floor. Put your hand on the upper corners of an open baffle woofer. Feel any flexing or vibration? No, corners are rock solid. And a spike on the corner at the bottom sees no vibration or flexing either. So the woofer doesn't transmit energy into the floor that way.
The way a woofer transmits energy into the floor is the same way that it transmits energy to the ceiling and walls. It creates room pressure. Now an open baffle woofer creates more of a velocity wave rather than a pressure wave. So it mitigates room pressure already.
Still there can be some flexing of the walls, but much less than a typical woofer system or speaker. So a damper can be used to absorb it. And there are a lot of different kinds of dampers.
These dampers are not isolators. They do not isolate a speaker from the floor. The speaker is still sitting on and coupled to the floor. You are basically adding a shock absorber.
The amount of improvement gained depends on how much the floor flexes and at what wavelength verses the effectiveness of the damper at that wavelength.
Keep in mind that you don't want your speaker to move. So if it is floating around or bouncing around on your dampers then they aren't working.
So keys to note. Focus the weight of the speaker on the floor to fewer spots. So three or four spikes is best. That makes all the weight focused on those small areas. That makes it harder to move. Above the weight you need a heavy damper that spreads out the energy or converts it to heat. So thick bag of sand. Something dense that has a different density than the spike. It is like a filter. A steel spike will only transmit certain wavelengths. And a piece of hardwood or a concrete block will transmit only a different wavelength. Stack up hard but dissimilar materials and you have created a filter that damps out movement.
So think spike, wood block, sheet of granite, blue tack or hard rubber bumper.... and make your stacked layers.