I have found that the very heavy brass tube dampers that Andy Bouwman of Vintage Tube Services sells make an audible and positive difference in the EF 86 tubes in my preamplifier, better focus of images being the primary benefit.
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