I’m giving the new Apos Ray 12AU7 tubes a spin in my BHK pre and I am quite impressed so far.
https://apos.audio/products/apos-ray-tube-12au7 36
Apos / Ray are cagey about their provenance (China, most likely) and they claim to only accept the top 4% of production, whatever that means.
At $180 per matched pair, they are priced near the top of new production tubes (e.g., Gold Lion), but much cheaper than almost any worthy NOS 12AU7s, and believe me, I have a ton of them in my stash.
WIth 100+ hours on them, they are quite impressive compared to the NOS Ciftes that preceded them, which were smooth and inviting, a bit on the warm side and not particularly incisive.
The Ray tubes are a different animal altogether–big, dynamic and quite detailed without any hardness or edge. They throw a huge soundstage, with powerful, yet tight and textured bass.
Worth a try…