Tried an Acoustic Revive RR-77 a few years ago and have been duly impressed. Since then Acoustic Revive has replaced it with the RR-777 and now the RR-888. Kemp has an SR-Plug. Space Technology Laboratory (Canada) has come out with four different models and there are several different units on E-BAY from Indonesia, Bulgaria, England, etc. There's even a unit from Less EMF being marketed by Sears.
I'm somewhat naturally skeptical, but there's no denying that this little RR-77 box has made the single biggest improvement in my system than any other tweak I've tried (and I have tried a bunch through the years).
So given all the new Schumann based products out there, I would be interested in what's working and what's not. The price range in my personal survey runs between about $70.00 to well over 3 grand. Any help in sorting these products out would be (as always) appreciated.