I hear no positive effect from any CD mat I have tried, but at least they are inexpensive. I also have heard no improvement from using cable elevators to lift speaker cables off floor. Then there is the whole Shun Mook stable of bizarre tweaks that are very expensive, I doubt if many of these are very useful, but I have not tried them presonally. Tweaks I use are Auric Illuminator, Bedini II, and Kontak cleaner/enhancer, and various isolation devices.
Biggest hype-worst tweak
I was wondering what everybody had found to be the biggest waste of time regarding tweaks-I've tried most-largely with satisfying results.The worst one for me was a Statmat (this months Hi-fi Choice has Jimmy Hughes still raving about the thing!)-a polythene floppy mat for sitting on top of your CD's-with weird markings-supposed to disperse static and make motherships land in your garden or something... Pure nonsense-had me pulling my hair out as it stuck in the tray constantly and my face twisted at the strain of trying to hear something/anything.....how my girlfriend laughed as she picked the thing up-you need help she remarked-I sent it back...and yet I fear I might have missed something Ben