Hello Oregonpapa if you are still out there...
Ref: your 2-12-11 experiment with two 12"x12"x2" marble platforms under each speaker. I would be curious about the performance of the marble if you removed the sandwich of damping material between the slabs. Would improvement result and possibly approach that of the 18x15 mapleshade set up? It seems to me that the sandwich of damping would kill the base response as described in the rocking on the carpet example in article at http://www.audioholics.com/education/loudspeaker-basics/speaker-spikes-and-cones-2013-what2019s-the-point.
Ref: your 2-12-11 experiment with two 12"x12"x2" marble platforms under each speaker. I would be curious about the performance of the marble if you removed the sandwich of damping material between the slabs. Would improvement result and possibly approach that of the 18x15 mapleshade set up? It seems to me that the sandwich of damping would kill the base response as described in the rocking on the carpet example in article at http://www.audioholics.com/education/loudspeaker-basics/speaker-spikes-and-cones-2013-what2019s-the-point.