Hi Tom,
If we put all of this in context, the actual floor-borne mechanical vibration from a sub or speaker is a relatively small component of the total output from a powerful subwoofer and/or full-range loudspeaker. It's the acoustically generated energy in the bass combined with the room's standing waves that set all kind of things in a room resonating, including the sheetrock, studs and wooden floor, often to an annoying degree at high volume levels (especially for easily annoyed neighbors in nearby apartments or condos).
Of course, as pmbuko notes, isolation pads would absorb mechanical energy but do nothing for the bulk of acoustical energy a subwoofer or speaker generates.
Regards,
Alan
