TAD rebrands selected Chinese tubes. In my experience they are more reliable than buying stock Chinese tubes, but are not as good as Russian-manufactured tubes. In another thread I mentioned testing a series of 6L6/KT66 family tubes in my Williamson amplifiers. The Gold Lion KT66s measured much better, producing more power and less distortion before clipping, than TAD KT66s. The Gold Lions also sound better, more open and textured. I stick with Russian tubes myself, and that includes rectifiers and small signal tubes.
