I use Isoblocks (laminated cork and rubber) which do a decent job of decoupling without sucking much life out of the sound. The bass is pretty tight, but has a certain warmth to it that I enjoy.
Speaker Bass
I have speakers that rest on carpet. I want to tighten up the bass. I have brass feet that do not penetrate the carpet. Should I get longer spikes or as a friend suggests isolate them from the floor? The carpet rests on wood under layment. There is a wife acceptance factor at work, too. All help is greatly appreciated.