Todd, I am on concrete. My speakers have powered woofers so there is plenty of energy being developed. I found the cheapo rubber/foam to really free up the music - bass tightened up and the higher frequencies became even clearer. For $2 of parts and $4 shipping you could give them a try first. Matter of fact, PM me and I'll send you 8 of them to try since I bought a box of 24 just to have at $0.50 each.
Going to Axpona?
Going to Axpona?