Need advice re: Tube dampers

I need an advice on Which tube dampers to use on a quartet of 6GK5 tubes in my CJ Premier Ten preamp.I just bought EAT Cool Dampers (red aluminum heatsinks)but turns out they're too big for my tubes.I currently have what looks like mid 90s fat black sorbothane? rings,one per tube sitting just below the top of the tube.Would i benefit if i use 2 thinner rings per tube (one at the top,the other one at the bottom),a kind that ARC sells for $2=95 apiece?What other options are out there?I saw those Creatura rings but read that they tend to thin out the sound which is a no-no in my case.Any advice would be appreciated.
When I tried Herbies on my quad of preamp tubes at mid tube, they dampened the sound so much that I took them off immediately and never tried them again. Given they are so well rated - where are you placing them to get the best sound - at bottom of tube, at top or mid tube?