@o_holter I recently installed a set of HFT's on my Magnepan 20.7s and I also have a set of 12 UEF panels that I borrowed from a friend. Since it is essentially impossible to do an effective before and after test I am completely open to the argument that what I think I am hearing is just a psycho-acoustic delusion. And the fact that I can't think of any real mechanism for those things to make a difference makes that even more likely.
Having said that, the biggest confirmation that these devices do something is that the sound seems to change when you move them around. I have adjusted the positioning from what Synergistic suggests and noticed changes, some for the worse and some for the better. It is still possible what I think I am hearing is just a delusion but the fact that I think I hear differences rather than no change is an argument for them doing something.
In my system I would say the biggest differences I think I hear are an improvement in the attack and transients in terms of sound. Things that are supposed to be crisp and sharp are more so. Secondly, I have noticed more specificity and depth in the soundstage. Overall, I feel they have made a real improvement and in a way that would be difficult to achieve otherwise. And if that isn't so, well I believe it is so and therefore my enjoyment of my system has improved LOL.
I haven't tried the "thick crystal necklace". Maybe it would have the same effect but I suspect not.