I've used the old stock DR in my Venice line stage, tried modern production found it dead sounding, did manage to find a matched quad of very early DR 6H30s, all the joy came back immediately. I gather that in some gear, the difference is not so noticeable. And as mulveling said, sourcing those is harder than some more rarified "grail" type tubes.
6H30 Tubes
Everyone says the sound of these tubes can’t really be changed, yet there are cheap as well as very expensive versions available. I use these in an AR preamp. Aside from matching the tubes, can I get a better/different sound going to a more expensive tube? My current tubes came from Upscale Audio and if I recall were well under $100 each, maybe even the pair. I know there's threads on these here, but maybe there's updates on what folks have tried.