I have suspended wood floors and notice with my Gallos that a tremendous amount of low frequency energy in getting into the floor and walls at moderate to higher volumes.
In conjunction with whatever else you do, you may want to look at the floor joist support directly beneath the speakers...some cross bracing may help. Some years ago, there were a couple of folks who added supports directly below the speakers extending down to the concrete basement floor below. Somewhat extreme but possibly effective depending on the situation. Decoupling seems to be a preferred approach with suspended hardwood floors. This typically involves some sort of elastic medium - a material with elastic properties, not a liberal
clairvoyant.
