should speakers be coupled or decoupled?

It is not science to say that something does not exist until you have an explanation for it. Theory in physics is great but it is a broad extrapolation from reality, not reality itself. In any case there will be many effects that can affect the sound and theory by itself can not tell us which is the critical one. If we are not to depend on our hearing what are we to base our decisions on? Being convinced by a theory is no different than being convinced by some one else's glowing testimonials. Neither is definitive, science advances by discovering anomalous effects contrary to accepted theory.

I can claim to have some knowledge of the working of science, I did my PhD research in it's history. I reiterate that what you are describing is not science. Quoting theory will not tell you in advance how something will sound, just how it MAY sound. If our ears are not the final arbiter of sound what is? In the old days there were stories of those who never actually listened to their systems, just watched them on oscilloscopes . Maybe the stories were true. As to cones, they COUPLE components, not DECOUPLE them. The makers of the ones I use, and sell, are very specific on this point and it should be obvious with a little thought. The purpose of the cone is to transfer vibrations as rapidly as possible [ ground, as they put it] to the floor. Decoupling the components involves PREVENTING the transfer of vibrations between the component and what it is resting on. How do you think a cone does this? See Star Sound site for their discussion. Decoupling is a totally different approach; Its leading exponent is probably Barry Diament, a prominent recording engineer, he has a web site. I have debated him on this point in the past. He also can produce elegant theory as to why his approach is better. As I really believe in science I am just at the point of ordering some FIM isolators which use the principals he espouses. I intend to see for myself which sounds better. I think I am right but I would like to know for sure. That, my friends, is science, all else is hand waving.

The technical description of the Star Sound approach can be found here. http://www.starsoundtechnologies.com/coulomb.html