in addition to a DS, BHK 250, and P10 in my system I have a Rogue Super Magnum 99 pre-amp. A very nice machine. (Aside, I would consider the BHK pre but need a tape loop out to drive a second system for my patio). Anyway, I had a nice set of 60s vintage Sylvania 6SN7s in the pre for about 2.5 years. System was starting to sound dull to me (who knows, could be hallucinating) so I went shopping for new tubes. Decided to buy a set of 1948 Sylvania Metal base tubes: expensive!! Wow!! Now I’m figuring out how I’m going to squirl away some money to be buy a back up set. How fantastic!! I hate/love this hobby!! To think these tubes have been sitting around since 1948 waiting to make my system sing is too awesome!