Opinions on tubes

I have a Sonic Fronties SDF-2 with the Seimens 6922/E88cc gold pin tubes and was wondering what other tubes people have used. like to hear from anyone with same D/A and there thoughts, has anyone upgraded to the mkII hdcd version? Is it worth the money?
What improved the sound of my tube amp and preamp was adding the little lead weights to the tubes along with damping rings, the added weight was a good overall improvement and cheap.
can you clarify on the lead weights (how/what/where/etc.)?