Schumann Resonator

I got 2 of these from Amazon...careful that free returns are applicable.  I charged them up, turned them on and holy moly.....they do help with my system.   What I hear is between instruments, a definite difference in upright and electric bass, wider know...all the good stuff. At first I thought it might be increased brightness, but is still the same in that regard.  I still can't believe it, and will listen again tomorrow (saved the packaging for the return)...but today, I'm about to keep them.
What are these supposed to do and how do they do it? I read the description on Amazon and still can't figure it out. Does it emit "waves" from a built-in speaker or something else? I see one review of someone that wanted to keep it under their pillow at night but it was too bright. 
I'm glad to hear that you have discovered this tweak (I hate to minimize it by calling it that) which is so affordable and effective. I started reading about it on these forums some years back, and then more or less forgot about it. I give Mahgister credit for making me aware of it again. It is so effective, and so cheap, it just doesn't make any sense not to try it!
I use two, and would not be without them.