Do tube dampers improve sound?

I use the Herbies Audio Labs Hal-o dampers on the 6922 tubes in my ARC LS-15. They did make a difference. They cleared up the soundstage a little and separated things a little better, but don't expect night and day difference with 6922 tubes that are low noise and low microphony, such as carefully selected and properly matched set of EH6922 tubes for example. WHats good about Herbies, is they come off easily and the never stick to the tubes due to heat.
http://herbiesaudiolab.home.att.net/

I even noticed that the placement of tube rings on the tube matters. If they are placed right in the middle of the tubes, they become too much of a good thing. But at the very top of the tubes, they provide a nice improvement. Although I didn't hear any drastic tonal changes, but separation, definition of instruments and overall soundstage clarity definitely improved. Dressing all the tubes in the preamp with Hal-O damping instruments doesn't cost much and I think it's a worthy improvement.
At least in my system it was.