Please don't laugh but I was wondering if the Chess board is acting as a damper and the pieces are acting as a diffusor?
I keep thinking the board is acting like a ceiling diffusor just sitting on top of the amp just facing up rather than down.
![](http://www.darkroommastering.com/images/wooden-diffusor1.jpg)
What happens when you remove the pieces on the board or change the pieces on the board? Was there a change in sound? Do you have different boards that have different weight or materials and is there a difference in sound?
This reminds me of a discussion I had with an older audiophile who told me there was a reviewer who found that their CDs put horizontally vs vertically in their rack and heard a sonic difference in their system. It was some kind of wall diffusor I thought.