Emission Labs 300B vs Shuguang Black Treasure

Brf,
For a while the KR 300b was the tube of top choice for Isael Blume's Coincident Frankenstein SET amp. He loved the sound but he didn't receive factory support for early failing tubes and had to discontinue their use. I know there are people who are using the KR 300b without any problems, the problem has likely been addressed is my assumption. Probably many of the earlier year models are fine, the question is which vintage do you avoid.
Charles,

The problem lies in the fact that there are a lot of NOS KR tubes around today being sold by "unauthorized" KR dealers who are "actively" misrepresenting themselves as USA distributors. If you google KR tubes USA you will get the USA KR distributor but when you go to KR's main website it makes no mention of said USA distributor and directs you to another USA site.

KR has a lot of rogue dealers who offer no warrantee support. My buddy bought a pair of ballon 300b which ended up have some loose internals and was not offered a replacement. He is so worried about a short, the tubes remain in a box.

I wouldn't recommend KR tubes based on my experience and knowledge. If one does decide to go with KR tubes, I would contact KR in the Czech for an authorized reseller. My 2 cents.

If your friend was in US I could test his tubes with my Amplitrex tube tester for free.

Jwm- Pls check your system page.

Pani;
i have exactly the same dilemma. i currently own the black bottles (2yrs), and wonder if i should continue with them(now the psane's), or buy emission. The emissions themselves present another so called dilemma, their regular 300b, or the xls version.
i have been happy so far with the shuguang-z's, however i dont know if the psvanes will be the same, better, or worse.
Trouble is that, and the emissions are about double the cost.

Audio nirvana is so difficult to reach ;) !