DIY speaker isolation base for a wood floor

Ok Geoff I'm trying your idea of springs and a granite slab or 2. I would assume 2 stacked would be better. I'm going with nothing in between. I'm picking up the springs Monday. I will tinker with that. I will then see if the sorbethane between the slabs is a bust with the springs. Maybe skip that and go with the spikes. Thanks for your expertise here and thank everyone else for there sometimes passionate opinions.

The granite slabs should be fairly large in dimension, maybe 18x18. 24x24 would be even better, more stable. If you can find one slab two inches thick, use that but only one slab. You want to reduce Center of Gravity height, not increase it. How heavy and tall are the speakers?

Use as many springs as you need to get the whole thing stable. Minimum 4. Might need more than 4. Did you calculate the spring rate of the springs based on total mass of speaker + Granite?

Thanks Geoff here is what I know.
102 lb load rated springs.
Spring constant 126.25 lbs per sq inch.
1.375" OD x 0.177" steel wire and 2.75 " length.
The slabs weigh 32 lbs and I  have four
The speakers are around 72 lbs.
I can get more when I go to town. I can't wait to try these. Thanks

It sounds to me like your springs are more suitable for a 400 LB speaker. The spring rate of the system is the spring rate of a spring x the number of springs.

Speakers are 42 inches tall.