I'm wondering how would I change the tone with placement of the tube dampers on the tube. I'm trying to get more warmth. I have a new Rogue Athena pre and its just a little bright due to the 6h30 super tubes. I have the old plastic Herbie's and they're pretty good. I need to get 8 dampers for my EL34's and at least 4 dampers for the 6H30's. I heard its too late to turn in the old dampers for the new ones. Shucks!