In 1991 I first experienced a tweak that had no earthly reason to work, yet it apparently did. A company called Shun Mook had a demo at CES where they placed and then removed their Mpingo Discs on top of a CD player and I heard a difference. I wasn't the only one to hear changes. All the audio journalists who experienced this unique demo heard the same sonic improvements when the discs were placed on the Magnavox CD player.
I should mention that I have a set of Mpingo dics, and during the twenty years that have passed since that demo, I have been totally unable to hear any differences when they were installed anywhere in my own home stereo systems.
So what gives? Are the home systems I've set up over the last two decades lacking in sufficient resolving power to reveal the discs' effects? I don't think so. But every time I've tried the discs they've proved completely ineffective.
I suspect that all the folks who participated in the original CES demo were "Shun Mooked." This is a psycho-acoustic phenomenon that occurs when you are in a room full of people who believe something WILL make a difference - and it DOES! It's akin to being the only non-committed voter in a room full of party faithful - by the end of the night you will be "a believer." The psychic force of all those committed brains makes you hear exactly what they are hearing. Or not hearing.
What did the Shun Mook experience teach me? I learned that while I may hear differences caused by mods and tweaks at a trade show or demo, I will never accept the results until I can duplicate them at home on my own system. Some devices, such as the AudioPrism Ground Plane, have proven over time to make a repeatable difference with different set-ups and components in various systems. Others, like the Shun Mook Mpingo discs, have turned out to be nothing more than pricy placebos.
I try to keep my mind as open as possible without letting my brains fall out. And while I'm still more than willing to listen to any demo that doesn't involve SPLs above 95 dB, before I cry from the rooftops, "This works!" I now insist on listening to the device at home through multiple systems.
In the words of Pete Townshend, "Won't be fooled again..."