To couple, or not to couple, that is the question

There seems to be a fundamental difference of opinion between those who would couple their speakers to the floor (e.g., with spikes), and those who would decouple them (e.g., with springs). I’ve gone both ways, but have found that I prefer the latter; I’ve currently got Sorbothane feet attached to my tower speakers, so that they wobble or "float"—much like the Townshend Platforms videos show for that similar, but more expensive, approach. My ears are the final arbiters of my listening experience, so they rule my choices. But my mind likes to have a theoretical explanation to account for my subjective preferences.

That’s where the question comes in. A very knowledgable audiophile friend insists that what I prefer is precisely the opposite of what is best: that ideally, the speaker enclosure should be as rigid and immovable as possible so that the moving cones of the drivers can both most efficiently and most accurately create a sound front free of the inevitable colorations that would come from fighting against a moving cabinet. He says that transients will be muddied by the motion of the cabinet set up by the motion of the speaker cones. And this makes perfect sense to me in terms of my physical intuitions. It’s perhaps analogous to the desirability of having a rigid frame in a high-performance vehicle, which allows the engineers to design the suspension without having to worry too much about the complex interactions with a flexing chassis.

Am I just deluded, then, in preferring a non-rigid interface between speaker and floor? Or does it depend on the kind of floor? (I get that most advice seems to favor decoupling from a suspended wood floor, and coupling to a slab; my floor is hardwood, but not exactly "suspended" as the underflooring structure is very rigid.) Or are there trade offs here, as there usually are in such options: do I gain something (but what, and how?) even as I lose something else (i.e., clean transients, especially in bass tones)?

The ears will win this contest, but I like to have my mind on board if possible. So thanks for any input you may have on this question.

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Springs will wobble if pushed at frequencies much lower to what the speaker is generating such that, at audio frequencies, they are as stable as they would be on spikes.

I had always thought that the best possible situation was spikes thru the carpet into the concrete ( at my house) floor.  With a LOT of urging, one evening I removed the spikes and replaced them with the GAIA feet from IsoAcoustics and realized that my preconceived notion was wrong.  Bass was more pitch accurate and mid-range smear that I was unaware of was suddenly gone.  These are rather large floor-standers (110 pounds each).  I have no clue as to why the GAIA's make such an improvement over spikes, but they certainly do and are worth the time/effort to try.  I have no affiliation with the manufacturer or distributor.

I agree with Eric, it is complicated and floor does transfer sound.  I tried to couple (spikes) and decouple (Vibrapods) and cannot say one way is better than another - just different sound.  I moved recently from wooden floor/basement home to one on the slab with ceramic tiles and resonances are completely gone, but it might be caused by different dimensions of the room as well - back wall 2x further away (less of the room effect at bass frequencies).  Vibrapods and such make speaker less stable - important with kids.  Spikes over large/wide granite slab on isolation (like Vibrapods) might work well.  They also sell in gardening stores, heavy as hell, garden concrete columns/pedestals - very cheap and way better than stands (if you need them), as long as you can tolerate such atrocity in your room.

Thanks folks. But my question was more theoretical than practical: as far as practice goes, I’m sure my system sounds better with the speakers decoupled on Sorbothane feet. But the theoretical question remains: WHY? It would seem, as my "expert" friend argues, that a rigid structure for the drivers would be better. It makes intuitive sense that the motion of the speaker cones will necessarily move the entire speaker enclosure on that "floating" platform, even if in only very tiny amounts. This—again, it would seem—should "smear" transients, especially at lower frequencies, which should result in a subjective experience of reduced clarity, locational specificity, and so forth.

Only Eric has addressed this, and he only very briefly. That having woofers closer to the floor would be better is consistent with my intuition here: the moment of inertia on a tall tower (49"), if the woofer(s) are mounted high, will be greater, and thus the movement imparted to the enclosure will be greater. As it happens, my speakers employ the "D’Appolito" array: two 6.5" woofers, one above and one below a dome tweeter, all three of them at the top of the tower. And yet, the speakers DO NOT sound smeared or compromised when standing on rubber. Why not?