Accoustical panels vs isolation platform

I had a couple extra accoustical tiles which i placed beneath my main speakers.  Seems to me this may be a good idea.  I get about six panels for about 20 bucks. 
 

Anybody else try this?  I understand isolation feet for a subwoofer and A need for rubber feet on main speakersto to avoid vibrating the floor, etc.  But these panels seem to accomplish a lot of things, and now I can slide them around if I want as a bonus.