I recently purchased two of the Black Sand Silver Reference PCs -- one for my McCormack DNA-500 and the other for my ARC SP9 preamp. I have to say that these are quite amazing power cords! There's an interesting thread out on AudioCircle...
http://www.audiocircle.com/circles/viewtopic.php?t=25799
http://www.audiocircle.com/circles/viewtopic.php?t=25799