Has any one else tried using thick marble slabs under their speakers?

[mgh13]

I've read a lot of posts about the improved sonic quality from using thick marble, concrete, and lime stone under their speakers. I decided to try some out, (I used 1.25” thick piece of counter top marble) and it really worked well for me, improving bass and mid bass accuracy. I also found a few extra advantages that even if they didn't improve the sound are still worth using.
1. Protects the floor from getting scratched when using speaker spikes.
2. Protects the speaker cabinet from getting scratched or dinged up from the vacuum cleaner.
3. They look great and really improve the stability of the speaker.
4. It's very easy to set up (a 1 man operation). When you spike your speakers to the marble you don't need to use the plates or cups and you can now easily adjust toe-in positions for different listening positions or when listening by yourself or with others.
5. Reduces noise caused from the floor vibrating. Especially laminate or wood floors. I've heard of people using items from pennies to beer bottles. Really? Not in my house and not with my wife! Regular thin tiles don't work on carpet and the mass isn't sufficient to properly absorb vibrations on any type floor and the weight of some speakers will break the tile.
This is a good DIY project for those who can, but for those who can't let me know I can hook you up to a website that sells the marble and some really good looking concrete stands.
If you have any comments I'm all ears, all I can say is they really helped improve my system.

Denon AVR 3310ci (runs low's), Outlaw Audio 750 (runs high's), (I run the pre outs from the Denon to bi-amp all 5 speakers) OPPO BDP-83 (soon to be replaced with a BDP-95) a Panamax 6300 line conditioner, B&W N 803 (front), B&W LCR-6 (center) B&W DM-601 (surrounds), Velodyne Optimum 12 sub-woofer, all speakers spiked to Audio Image Technologies Designer Series speaker stands (www.2ndflooraudio.com), Directv HR24 HD DVR, Panasonic TC-P50G20 HD Plasma TV