Hi @reimarc
The reason I asked about the Linlai's is that these are supposed to be good tubes but the stock you received could have been different. There is a thread about these, the ones with the E are supposed to the best and the Linlai letters on the tube are running vertically.
There are some others the letters run horizontally and some have described these as different.
That's why I was trying to find out the ones that did not work for you which specific type were