Better sound

I use a pair of extra large Symposium Svelte Shelves under my speakers. These are designed to dissipate vibrational energy as heat (vibration from the cabinet is transmitted into the shelf which has a rubbery core). This acts to tighten up the bass and reduce the amount of energy that is then transferred to the floor.

I have heard a number of setups that use such vibration dampening approaches and it is quite effective--provided that such dampening is desirable. Each setup is different, so this approach may actually make the sound too dry and analytical if additional dampening is NOT what is needed.

Experimentation is required.

Using either sharp feet or vibration absorbing platforms essentially changes how vibration in the speaker cabinet is dissipated. An absorbing platform does not increase the shaking of the cabinet, rather, it conveys that energy into the platform and dissipates that energy as heat (from molecules in the elastic core rubbing against each other. Pointed feet direct that vibrational energy down into the flooring for dissipation by the flooring. If the flooring is very solid (e.g., concrete or hardwood on concrete), the energy is again dissipated as heat with very little radiation of sound from the flooring (because the flooring is very solid and massive it is hard to move, and therefore, does not readily vibrate). If that flooring is also covered by carpet, whatever sound is radiated is mostly absorbed by the carpet. If the flooring is wood on some kind of suspended structure, there is greater chance that the flooring itself will act as a kind of soundingboard and radiate sound. This could muddy the sound, or alternatively, it could add some warmth to the sound that is needed by the system.

Putting some sort of solid puck under sharp points to protect a hardwood floor actually prevents sharp-pointed feet from working fully as they are intended. The lack of intense pressure on a small point reduces the coupling of the footer to the floor so less energy is transferred to the floor. That means more energy reflected back toward the speaker, and therefore, more "shaking" than the use of no puck under the foot.

I don't know of any way to reliably predict whether one approach is better than another other, and instead, I rely on experimentation. Having helped with a lot of setups, I can only report that use of absorbing platforms is often the preferred approach (perhaps a little over 50% of the time).