I wanted to add my $.02 - I have a subdude, and in my case, it did reduce the vibrations that was previously being transmitted when my sub was directly in contact with my (laminate) floor.
It was easy to observe the change without resulting to subjective listening tests with my setup. My center speaker sits on a shelf that isn't quite level (it's angled slightly downwards). After watching movies with LFE-heavy scenes, I used to noticed that my center speaker had 'slid' down the shelf by a couple of inches.
Now with my sub sitting on top of the platform, this no longer happens.
It was easy to observe the change without resulting to subjective listening tests with my setup. My center speaker sits on a shelf that isn't quite level (it's angled slightly downwards). After watching movies with LFE-heavy scenes, I used to noticed that my center speaker had 'slid' down the shelf by a couple of inches.
Now with my sub sitting on top of the platform, this no longer happens.

























