I agree with carlsbad 2. Spikes just minimize the surface-to-surface contact. The only good use that I see for spikes is to keep a subwoofer from sliding around on carpet. I used to have a hum problem with my turntable years ago whenever I would turn up the volume loud. I tried everything without great success. I then built a spring-loaded platform to set the turntable on and the problem was completely solved.
Speaker Spikes - Working Principle
Vibration damping obvious makes sense (in speakers just as well as in cars).
That involves 'killing' (converting into heat, through typically internal friction) kinetic energy. So any sort of elastic material (rubber has lots of internal friction) makes sense.
And then there are spikes. Using a pointy hard object and pair it with a softer, elastic material (to deform, and kill kinetic energy) can work; think metal sharp spike into carpet or wood floor.
But what is the idea behind pairing fairly unelastic metal (brass for example) with similarly unelastic (brass, stone, etc) material (example photo provided)? Only thing I can come up with: LOOKS good and makes owner feel good thinking its an improvement (works only for Audiophiles though),
Even more curious: are they ENGINEERED "spikes" (vibration dampers or shock absorbers) for speakers that are TUNED for the frequency (and mass) that needs to be dampened? Can piston style fluid dampers be designed for the high frequencies (100, 1000, 10000 Hz) using geometry, nozzles size and viscosity of the fluid?