Under my tower speakers -- Isoacoustics Gaia, other options?

Or get some 2” restaurant pads, ones that the,cooks stand on all day, spikes would sink in and never move. 
 

I used racketballs in my rack years ago, worked a charm, and your not getting taken advantage f by the eejits who say “use our modular half circle moon isodampening pads, they will make the music reach out and lightly stroke your ears and neck like a bunny fart. 
use your own ingenuity.  Plus. U have brag rights of saving hundreds of dollars for which you and your wife can get a nice steak and blue cheese med. rare only!

@arcticdeth 
Your DIY suggestions include putting cutting boards, or large flat stone squares, on top of the situation I describe -- which is carpet on a concrete floor. I don't see what putting your suggested hard things on top of another hard thing, my the concrete floor, makes sense. Can you explain?

Thank you, thought floor was bare concrete. Which,would benefit from a block or a thick rubber pad.

the racketballs sure helped,dampen,vibrations in my rack

Hey hilde45...

In my long experience as an Anti-Resonance Cop (especially under the hood) masonry rarely works.  If your floor carpet is thin enough, you might try to find some vintage golf cleat spikes and weigh down the speakers:

50_31067b_lg.jpeg (1200×1600) (iconicauctions.com)

I've also been pleasantly surprised with bookshelf monitors atop carefully weight measured Vibrapods, isolating in a somewhat 360 degree fashion, despite most preferring mass loading with loudspeakers.  Aluminum isolation cones can work well and are reasonably priced.  As stated, adding some mass to the top of your loudspeakers can prove effective depending upon the approach used.  Sound dampening the boxes internally and/or externally can prove extremely rewarding.  

More Peace, Pin           (bold print for aging eyes)

isolation recommendations without specifying floor type are meaningless.