I noticed that my new Shen has a wooden disk glued to the back to serve as a pad on which the post rests. My Engelhardt did not have one. I can see how it might assist in preventing the post from popping through the back, but it also makes sense that it would diffuse and otherwise impede the post's ability to transfer sound energy into the back. Is this pad the exception or the norm? Am I correct in assuming these pads are limited to plywood basses? Do any of our fine resident builders use them?