@Mr VI

Your question comes up all the time. I will answer it in two parts:

First, re: concrete - having a decoupling device in place absolutely makes a difference when you have a concrete floor! Many people are under the misconception that concrete is inert. Concrete is FAR from inert. Concrete moves and shakes. Typically, a concrete floor or walls will have more mass than typical wood-frame construction. So it takes more energy to get more mass to move. But when that greater mass DOES move, it actually transmits sound energy more effectively because it is a denser material. Ever seen that famous film of the concrete bridge rolling like a wave when a strong wind got it moving at its resonant frequency? Concrete is anything but solid and inert!

In your case, what might actually make the SubDude/ GRAMMA less necessary is your thick carpet. As I said, a thick carpet pad will already act as a decoupling device. The question is whether or not your subwoofer or tower speakers have managed to couple to the floor simply by crushing the carpet under their weight or if they have "feet" of some kind. If your subwoofer or speakers have "spikes", "cones" or "nubs" on the bottom, you can be fairly sure that those "feet" will sink deeply enough into your carpet that they will act to couple your subwoofer/speakers to the floor. If your sub/speakers have "feet", then the SubDude/GRAMMA will very likely still make a noticeable difference. If your sub/speakers do not have any "feet", then it is much harder to predict. The whole point though is to "float" your subwoofer/speakers so that they do not couple with the floor. If your carpet pad and carpet already achieves this "floatation", then the SubDude/GRAMMA won't make much of a difference. But any sort of "feet" will pierce or sink deeply, and just a very heavy sub/speaker might simply crush even thick carpet.

One easy way to predict: if you go into another room while bass is playing, can you easily hear the bass in that adjacent room? If so, your subwoofer is almost certainly coupled to the floor! As Ara said, with the SubDude in place, the "bleeding" of bass into other rooms is cut down dramatically! If your thick carpet is already effectively decoupling your subwoofer, you won't have this "bleeding" of the bass into other rooms to begin with!

Regardless though, concrete is never a reason to forego decoupling. Concrete construction will shake and decoupling makes a very noticeable improvement, just as it does with wood-frame or metal-frame construction.