I have also written this elsewhere. My Rogue Titan Atlas Magnum uses 4 x KT 120 power tubes, now Tungsol KT120's are not physically or ethically an option & the Shuguang factory has burnt down, buying the Shuguang Treasure KT120's described by many including the Stereo Times as the best available, bought from an unknown source even NOS could be subject to being seconds or worse.
I don't know whether the Psvane KT120's are still available, I have been lead to believe they were made by Shuguang I contacted Mark O'brien at Rogue Audio about using KT150's he said not viable so by extension KT170's are not an option either I have no wish to melt a transformer.
My tubes are several years old biased at 40Ma that's 35Ma on the gauge + 5Ma due to a resistor? even biased at such a low figure they won't last forever. Lets hope the Chinese Government builds a new Shuguang factory & starts production off KT120's.
If not what do I do... I tried KT 88's when my last set of KT 120'S needed replacing KT88'S were the original fitment in the Atlas Magnum, I have as stated used KT88's they sounded anaemic in comparison to the KT120's I have thought about them may be a poor if only option to my ears in my system.
Ant thoughts...