Hi, Kenreau. The goal is to get the speakers performing to their best potential. Holding the baffle as vibration-free as possible usually accomplishes this. At the same time, you want the speakers' design parameters, i.e., the resonant qualities of the cabinet woods, internal bracing, and other factors to remain unfettered. If the speaker is designed to "breathe" a little, you want to allow that.
The problem with "draining" vibrations is that vibrations don't drain as well in real-life as they do in theory. A cabinet suffering from some of the higher frequency vibrations that cause glare and other distortions will sometimes just jitter around on rigid material. Vibrations that are drained to the floor become floor-borne vibrations that can mess up the rest of your audio system. Vibrations simply don't follow the rules; they go every which way, traveling readily between and through hard materials. They'll reverberate right back up the way they came, too.
Decoupling with compliant materials like Sorbothane is usually worse. Your intuition about compliant interface, with speakers, is correct. With compliant materials, the idea isn't to let vibrations dissipate, but is to absorb vibrations (transfer the energy to heat). Rubber and Sorbothane, and most squishy materials will absorb some vibrations but yet by their compliant nature will also allow the cabinet to vibrate unconstrained to some degree. Speaker drivers will then drive even more cabinet vibration. Then, the rubbery materials will introduce resonances of their own into the cabinet that affect the speakers' drivers. Any benefit you get is usually at the cost of some detrimental trade-off.
With loudspeakers, rigid coupling tends to deliver a harsh, rigid musical result. Compliant decoupling often gives ill-defined bass and some loss of high frequency articulation.
The solution is something in-between, something that's neither squishy nor hard. Herbie's dBNeutralizer material used with Big Fat Dots is formulated specifically to address this loudspeaker/stand interface. The material is relatively hard and rigid, yet just compliant enough to block the transfer of vibrations and to intimately absorb unwanted cabinet vibrations. Natural qualities of the speaker woods are tamed but not conquered, allowing speakers to perform as they are designed to do.
With the occasional exception of very small monitor and desktop speakers, dBNeutralizer provides the best interface we know of with just about any speaker and stand. Speakers that rely on lots of rigid bracing will work optimally, as well as cabinets designed to "breathe." Harbeth speakers, with a "favorable resonance" design approach, do exceptionally well on Big Fat Dots (or Square Fat Dots).
Depending on speaker design, results can often be further improved by placing a granite slab on top of each speaker cabinet, filling hollow stands with sand or sand/lead shot, internal cabinet damping with rope caulk around speaker baskets, wire connectors, binding post mounts, crossover mounts.
With lots of speakers/stands, you might get a satisfactory improvement with cones, carbon discs, refrigerator magnets, and other devices. Even Sorbothane. But in most cases you can do better.
With 40.1 speakers at 75 pounds on MDF stands, the best solution is virtually a no-brainer: replace the Sorbothane discs with Big Fat Dots. Your speakers will thank you and breathe easy.
Steve HerbelinHerbie's Audio Lab