Hi,
I have used Gaia 2's under my loudspeakers which definitely improved the their sound. Because I'm I a tinkerer by nature, I replaced the Gaia's a year later with heavy, slightly damped compression coil springs that I found on Amazon. Shockingly, the homemade version sounded better! (Both forms of isolation were tuned to 5-10Hz.)
However, in the end I succumbed to forking out for the Townshend Seismic Isolation Podiums. They are stunning: far superior to both previous isolation efforts and completely freeing the music from the constraints of the speaker cabinets. Probably well worth their large price tag...
Go for the best!