As I bought this to replace my old stock tubes in a Fender Twin 65 W from the 80s, I can't really compare the actual brand to Groove Tubes, Sovtek, or others. I can just compare them to the old worn out stock tubes of my Fender Twin, which I can't remember how they sounded.
Needless to say, when changing it out, I had to change out every other tubes as well, and I can't really compare this tube on its own. But the sound was like the amp was new, I think it was even better. If you have a brand new amp it's nothing to "better" with changing out to this one. You'll better of trying to buy from esoteric and special tube retailter instead. At a price though. TAD are no frills, and works a charm. This review is made 1 year after I put them in, and they still sounds as when I bought them, regular playing.