I had constant problems try to get my speaker stands to spike though my thick carpet / underlay ...into my wooden floor boards and be level
Tried longer spikes ..cutting carpet ...custom made spikes ...
In desperation I ran 8 heavy duty cross head screws into the floor through the carpet etc and set them just below the carpet pile level
Then the stand spikes just dropped into the cross head slots ....
The improvement was very noticeable indeed
Many years ago we did a simular thing with Isobariks. You put metal feet on the bottom of the stand which had a concave bottom surface. You then drove concrete anchors through your carpet and underlay into your floor, (here in sunny Perth most floors are concrete), to align with the feet so the head of your anchor engaged into concave cup on the bottom of the feet.
First time I was shown this I nearly died. I had started with my Isobariks on Spendor BC3 stands, with castors no less. Mr T ripped my castors of leaving just the spindles. Huge improvement. Then we graduated to the first Linn stands with coins on the top surface, then with spikes on the top and bottom, and now the evil Linn guy was showing me this.
The concept of mechanically coupling your speakets to the floor, with the added elegance of a high pass filter a la spring/tuned plate and or frame was first explained to me by JV when the SBLs hit our showroom.
I have a floating laminate timber floor on concrete so my S400s sit on high tensile concrete anchors. I have over sized holes in the laminate flooring so it doesn't touch the anchors. I did this after living with the system for a few months. Huge improvement for a few dollars and a tense afternoon getting it all to happen.