Speaker Spikes - Working Principle

I had fine tuned the compressive and damping load of concrete on top of my speakers acting on the  two set of springs near 100 grams of fine tuning by ears with near 80 pounds of concrete ...( this was with my big speakers, with my actual very small speakers nothing had changed bu t i dont need springs now )

In my experience a sandwich of various materials is necessary under them and not only springs ...My speakers were relatively isolated by coupling/ decoupling using various materials not only damped....The two set of springs were powerful because compressed with different weight force they were able to decrease internal resonace in a way one set will not do ....

@mahgister I can see from your description about mounting a Speaker Cabinet you take your investigations into tidying up a sonic quite seriously.

I have a substantial supply of Cork Pads, they regularly find a place as a additional tier in an assembly. My interest in Granite has a 30ish year history of using it in multiple configurations in a support structure.

On my Cabinet Speakers my the Top Weight is a Large Lead Metal Block rested onto four 1/6" Cork Pads. The Lead Blocks then has approx’ 20lb of Steel Dumb Bell Weights sat upon it. Moving this weight around to different resting positions on the Top of the Speaker does have an impact where sonic or box coloration are able to be impacted for the better/worse.

I am a ESL Speaker user as well, so the Cabinet / Driver issues are easily by passed if wanted.

I thinking along the lines of @yoyoyaya 

I have a pair of tall, thin B & O ‘pencil’ speakers.  I have rubber feet on them as they’re on a concrete floor.  But if I move them onto an area rug, they easily rock and could be knocked over.  I think the purpose of spikes is to concentrate the weight to a thin point that can penetrate between carpet loops or piles.  This would bring the weight to bear on the firmer surface of the carpet backing.  The plusher the carpet, the more they are necessary and effective.

@tcotruvo - to further amplify your point (no pun intended), I originally had my Wilsons (which weight 400lbs each) directly on my carpeted floor (with thin pile carpet). I subsequently spiked them once I had their position optimised and the improvement in sound quality was significant. What surprised me was the degree of improvement in resolution in the midrange as well as the bass.

@yoyoyaya  Wow!  400 pounds!  I would guess once you have those on spikes you wouldn’t be moving them around.  Interesting that even with that weight and thin carpet the spikes still were an improvement in sound quality.

@tcotruvo Yes! I mentioned this as a case study because there can be a mistaken assumption that just because something is very heavy, it won't move around. However, at the risk of provoking the ire of the OP, the spikes not only stop reactive movement of the loudspeaker cabinets arising from the motion of the drive units, but they also stop the bottom of the cabinet from coupling directly to the floor and turning the floor into a giant resonator/soundboard. In the specific case, the floor is actually quite well damped as it composed of two different layers of wood, a linseed oil based composite and carpet. But...