I've done it. It makes a noticable difference in the effectiveness of the panels. I cut 1/2" x 1" standoffs and screwed them into all four corners of the panel in back. Then I bought a sheet of those small rubber peel-off circles for furniture and put one over the screw heads so it would not scratch the wall. Go for it.
I've also found that home-built panels just don't sound as good as Echobuster products, even if I try to get the same wood and foam. Something about that wool fabric maybe?
I've also found that home-built panels just don't sound as good as Echobuster products, even if I try to get the same wood and foam. Something about that wool fabric maybe?