Ok, here goes, might be treading into deep waters, we'll see, a contrast in two systems with Mapleshade board.
My floor is suspended yellow pine, very soft.
Friends floor is deep concrete slab with hard wood, a very hard surface. (Pierre Sprey says this is a horrible combination.)
My speakers are Shahinian Arcs, four feet are some kind of hard rubber or plastic (again Pierre says this is very bad)
My friend's speakers are Rega R9's, twice as tall, have four spikes connected with some special basket.
At my house, after putting small brass cones (not Pierre's) under the maple board, nothing between cones and flooring, the sound is amazing. Best surface the speakers have sat on so far. The shahinians have always felt very wobbly, especially on my soft floor. Now they at least sit very flat with little to no wobble.
When placing the boards under the Regas, same set up, although we did put pennies between cones and flooring, his is much nicer flooring. There was instantly a height issue for one of the fellow listeners, tweeters going pretty high past ear level. Sound was tight, yet lost the bloom necessary to really sound fantastic. So in his situation, not a good thing. There was no smearing or dullness as some of you have commented, yet too lean. His speakers sit very well on his hard flooring, no wobble to speak of.
So, in his room, which Pierre states should be better, it wasn't, and I would have wanted my money back.
In my room, I'm still doing some fiddling, but you couldn't wrestle them out of my arms without loosing one of yours. I truly love what they do here.
My listening panel is coming over later to judge me, and the boards. We'll see....
Maril, could you give more info on the product you mention? website?
Don, Mapleshade does make custom sizes, and in his catalog has I saw a 24" listed.
In summary, in my softfloored room the boards bring such a new level of clarity I'm totally gobsmacked.
Oh, to answer earlier about birch, it was nice, but had a grainier quality to it. Perhaps it was just the type I used, Lowe's 2by2 by 3/4.