The skinny on Mana sound bases for SBL's

I've had my SBL's for about 4 months now. Generally, i am pleased with the performance. However, one aspect still bothers me considerably; and that is the "chesty" veiled quality of the lower midrange. In the two rooms I have had them set up in (the current one of which uses a plaster covered cinder block wall behind the speakers), the lower midrange is colored and congested, simply refusing to break free from the box. I have no proof, mind you, but I get the sense that the problems I am experiencing (after having taken the steps outlined below) is related to the speaker/floor interface and the proximity of the speaker to the wall.

Now, incremental improvements have been made. Moving the 250 from the floor to the rack has improved this somewhat (voices, in particular) as well as moving the pre-amp from on top of the cd player to it's own dedicated shelf. This has also removed weight from on top of the cd player, which I also think has helped matters. But, I'm looking at the next step.

I'm considering two options. First, what can i expect from Mana equipment racks? Currently I am using a short two shelf rack from England (could be sound org--the tubing looks identical to the tubing on Linn Kan stands). Second, I'm also considering Mana speaker stands for the SBL's. I'm thinking that the speaker stands might make the greatest improvement as I'm not confident of the speaker/floor interface. The floor is concrete with padding and carpet (thin, but very dense and tough). Even after pushing the speaker spikes through the carpet, I am not confident all of them sit on the concrete below with equal force. I'm hoping the Mana stands will improve this.

Does anybody have any experience with these.

Ps. Am also considering a demo CDX, but am not convinced this will solve the problem.

Judd