Interesting stuff. Have anyone tried just blackening the edge without cuting the edge off to see how much was the effect was due the beveling and blackening the edge?

Also could you tell easily whether the CD have been bavel just by inspecting it with your eyes or hand. If it is not easy to tell them apart I would thought it would easy enough to post a pair of CDs around for people to listen at home using a greater range of players themselves .... like one only with the edge blacken against another bevel and blacken to see which one sound better.