My Schumann Generator has Arrived

I received my Schumman Generator on Saturday and I was finally able to try it out today. I tried it centered between the speakers on my rack at about 3ft from the floor. I really couldn't hear much of a difference. I moved it around the room and placed it on different surfaces all about 3ft from the floor. I listened to the same song, all the way through, at each location. I still didn't hear anything different. Then I placed it on top of one of my diffuser panels that is centered between the speakers behind my listening position. This is about 6ft from the floor. Now, I definitely heard a difference. The sound stage widened and the instruments had a more defined space within the sound stage.

Now for the questions. Would higher work even better? Is there a sweet spot for the distance from the floor that has worked for you? Does more than one generator improve things?