I have used both the Ensemble Tube Sox and the Top Hats for my small signal tubes, neither of which are inexpensive. I find the Top Hats to do a better job of focusing the sound and images; the effect is not huge but makes a difference to me. I think you might want to try the Audio Research small signal tube dampers, which are pretty inexpensive and are reported to be effective; at least that way you won't be out an arm and a leg if you don't notice a difference. I have not tried any dampers on the large power tubes I've used (6550s, KT88s); I know of none, and my practice has been to isolate the amps themselves from vibrations instead. Good luck!
