It's an incredible super tube, that sounds unlike any other tube in the family or any 12AT7 or 12AX7 as well. The transparency/detail is stunning with more nuance than I have ever heard, combined with texture you can feel and an organic richness that adds weight to the notes but never steers into bloated as the speed is insane with tight hard hitting bass, mids and vocals so lifelike sounding it's scary, and a very airy and extended but smooth and fatigue free top end and then on top of all that the staging is so massive and holographic it really is in a league of it's own. I call it a super tube, because of the sonics and also because it is rated for 40,000 hours. The price is insane, but unfortunately it's the going rate these days. I can tell you this, it's been a revelation and big ease off my mind and bank account, not looking for tubes anymore, as I know nothing can top or come close to this one. So, I definitely think it's worth the price of admission, as a "one and done" kind of tube purchase.
Thanks for your explanation, really intrigued now. I was thinking of replacing pendant with Cayin HA 300 mk2 which use 2 x 300b and 2 x 6SN7GTB. I know 300b are very difficult to find, is that a tube you have experience with? I will start with stock GoldLion 300 and Tung Sol 6SN7GTB but will look to step up eventually.
Do you have any thoughts on tubes equivalent to G73R which I could look in to for Cayin. From what you have said about G73R I might just hold on to pendant or get something else which could use this tube down the line.