I've lived with much tubed gear glowing with many tube types and hundreds of variants of these. I've come to a few things. You will never know how a tube sounds until you live with it and gain experience with it with your ears in your gear. Tube cost and sonic performance aren't necessarily positively correlated. Often that flea-market-priced humble-brand tube sounds better than that expensive NOS uber brand/reputation tube. And that there is no one magic tube that is perfect. Tubes can alter the sonics of piece substantially, but typically there are favorites, and several of them. (Also, learn to positively identify a tube by what's in the bottle, less than the ink on the outside; this way you are certain of exactly what you have and what you might want to talk about/share with others)
I have a very (very) large selection of 12AU7 family tubes. Because of the Crack, I now have a very nice selection of 6080/6AS7Gs. And I have a good handle of which flavors of these tubes I prefer in the Crack. I feel the Crack always sounds great, and a few favorite tubes take the sonic fun even further for me. I've only used Drop Sennheiser 6XX and 58X with the Crack, for reference. (I am curious what some other high impedance headphone brands and models might sound like with the Crack, but haven't gotten there, yet)
What I'm asking this group about are some "odd", "rare", oft-very-pricey 12AU7 types that I'm seeing more of more recently. I don't have any of these. I'm wondering whether people here may have some experience with them that they'd like to share.
Among these are:
- Italian Fivre brand
- Any OSRAM or GEC
- Telefunken G73-R
And, how are some of the more current production premium 12AU7s:
- Psvanes
- TJ Full Music
Love to hear what experience people have had with these tubes.