I copy and paste some great quotes from brownsfan made recently on this forum.
@brownsfan noted three types of issues -- without mentioning the seismic one:
movement of the speaker cabinet back and forth and side to side due to Newtonian action reaction caused by the driver motion
cabinet vibration also due to the drivers motion
floor resonance being transferred back and forth between the speaker and flooring until it finally dissipates.I did not include vibrations transmitted to the speakers that have its origins outside the confines of the listening room as a 4th type of kinetic motion because the medium through which those vibrations are transmitted is the room flooring. So my type 3 above is inclusive of anything that is transmitted to the speaker via the flooring.
In addition, I don't think anyone has said that such vibrations are not audible. But I did say that they are probably orders of magnitude less significant on concrete than they are on typical wood subflooring over a crawl space or in a second floor application. In my estimation and in my experience, the worst offender is usually type 2 if one is on wood flooring. If not, then it would appear that type 3 vibration is the more significant.
The problem here is that we can't determine with any degree of certainty which of the 3 types is most significant in our particular setting. Another problem is that addressing one type of kinetic energy may exacerbate the other two. This is why I don't hear many people claiming spikes are the answer.
The answer here is finding a way to rapidly (instantaneously would be ideal) convert these three (or 4 if you insist) types of kinetic energy to heat. The idea of isolation only works if you are isolating from an external source (seismic, as example). If you are talking about type 1 energy, you might address the movement of the speaker using spikes. But the law of conservation of mass and energy tells us that the energy that wanted to move the speaker and now can't, must express that energy in some other form. So spikes are converting the type 1 energy to a combination of type 2 energy plus heat. Thus, if type 2 energy is worse in terms of audible effects than type 1 energy, spikes could make your speakers sound worse. And spikes can't do anything at all to address type 2 and type 3 vibration.
This same argument can be applied to products designed to address type 3 or type 2 energy. Unless a particular device is capable of converting all three types of energy to heat, and doing so rapidly and efficiency, the device is robbing Peter to pay Paul.
I really think the manufactures that are super engineering their speaker cabinets have recognize what I am saying above. That is what these super rigid cabinets are doing. They are efficiently and rapidly converting type 2 kinetic energy to heat.
For those us that don't want to pay more for our speakers than we did for our house, we are forced to look for products like the Townsend for a poor man's solution, and the reality is that we are going to have to try some different types to see (hear) what works best in our particular setting.