I had the tested Tung-Sol KT-120. Installed on the Sonic Frontiers for quite a while. I installed these new PSAVANE KT-120 on the same amp hooked up to the top of the line Pathos « In Control « pre-amplifier. Speakers were the ProAc Response D20 R ( ribbon tweeter) and later, the new Martin Logan Electro-Motion hybrid electrostatic speakers.
Upon installing & biasing the new tubes on the D20R, I noticed a right away increase in transparency , detail in resolution. It became even more obvious when I upgraded the speaker cables to the new Cardas Cygnus. Also, an increase in depth very noticeable with either set of cables.
Also with both set of speakers, there was no brightness at all with these new tubes. No forwardness either. Overall, these new KT120-(Z CB)are definitely an upgrade over the Tung-Sol. And so far, they have been very reliable. And they look good too.
Have a good day,