I am going to commit blasphemy.
I have a NOS Mazdas that replaced Psvane ART series 12AU7s in my preamp. The Psvane ART had replaced Gold Lions. And I love how the Mazdas sounded so "natural" in my system. Used it for almost 1.8 years and they have a warranty of 2 years.
Since I wanted to save the Mazdas for future, I ordered the new Psvane Horizon 12AU7s. Initially they sounded alright - no great shakes. But after about 50-70 hours they did change. Since I listen on a daily basis, I did not realize how much they improved. But after a month or so, I decided to put the Mazdas back into the system, just to see how they would improve on the Psvanes. But long story short is that the Mazdas went back into their storage boxes and I dropped the idea of ordering one more pair of NOS Mazdas. The bass on the Mazdas seem bloated. I am not into that "warm" sound. The Psvane sounds more neutral and extended to me.
There - I did it, and probably lost all credibility on this forum.