BE718, you seem to actually be properly informed and have something genuinely helpful to offer. What is your take on spikes under speakers? I struggle with a 2 foot void beneath a large suspended wooden floor. Recently I swapped out the spikes for some sonic design Sorbathane pads under my large floor standing speakers. The audiophile consensus seems to say spikes sound best but the pads seem to have improved things.
Obviously I could try spikes again and listen, but I'd like to understand it better.
Also I've added other variables at the same time; a much more powerful amplifier and radically different speaker position, so I'm not sure what has caused the improvement.
Well. Think I would need to understand a bit more about your situation.
Spikes will hard couple the speakers to the floor, so if your objective is to minimise speaker vibration from getting into the floor then it's not a good way to go.
However compliant isolation would need to be correctly designed for the mass it is supporting, and as Keith says, a compliant support does need to be of the correct durometer. Sorb pads may help, but without measurement difficult to know how much and at what frequencies they have been effective.
Is your problem vibration being induced into a turntable, or is it just a general boominess to the bass? If it's the latter then isolating the speakers is not the solution. The room modes are dictated by the room dimensions and can only really be tackled with passive treatments or digital room eq. Let me know more.