I've been using Isoacoustics Gaia's under my speakers for years and think it's one of the best  improvements I've done. I'm actually surprised more speaker companies don't offer some sort of decoupling for their speakers as an option.

When I was in a carpeted listening room I had the metal cups they sell to punch through the carpet and give the footers a solid base to rest on.

For a less pricy option the Magichexa anti vibration pads work well too.