I used the Herbies dampers too on my tube integrated and have to say I could'nt hear a difference. Interestingly, HiFi News here in the UK, did a technical report on a number of tube dampers, including the pearl ones, though they are coolers too of course, in this months edition. They checked for microphony with and without the rings and found very little difference. Does'nt mean they are right of course, accurately measuring these things is'nt easy.
Do tube dampers improve sound?
I recently purchased a tube pre-amp and several NOS 6922 tubes (EH, JJ Tesla, and Philips). Should I consider buying tube dampers? Do they really help the sound? Thanks