12au7 tube?

Elrog 300b = $3,500 pair

I  spent $450 for very close tolerance within 2% medical grade Telefunken with the red tips worth every penny and last for years.

if you want a very good modern tube -12au7 

at APIs audio  Rays select tubes  hand picked closely matched made to a very high standard and a full 1 year warranty for-under $200 . I have the Rays big bulb 6SN7 

complementing the Tele 12AU7 in my LSA preamp is sounds very good .

Rays select 12AU7  

https://apos.audio/collections/top-sellers/products/apos-ray-tube-12au7

Ray tubes ? Made in China or where ?

I like Telefunken very much. Always found them to be very open and musical. They last for yrs. In fact all of my tubes, doesn’t matter what brand last and have never worn out. The only tube I remember having problems was the Sylvania triple mica black plate 5751.  It’s maybe considered one of the top 5751’s but for me always had a high failure rate.  Even all my power tubes have lasted these 30yrs because I have several amps and I use all my amps so my tubes have never failed except for going faulty.  I like the 6SN7 tube and I have a lot of the true Sylvania Chrome  Domes made in 1952-53 which is a really nice tube.   Also have the 1940’s Holy Grail 6SN7 Tung Sol round plate smoke glass.    For me, I liked many many of the different vintage 12au7’s including the Mullards but my favorites were the Amperex.    I felt Amperex had everything all in one tube. There are many different versions of Amperex 12au7’s, I liked Old World Logo and the 7316.