I think the "real" Amperex tubes do have some sort of magic. However, it is going to be hard to find a real Amperex and there are many different types and releases of the Amperex 6sn7 tube.  If you can find a real Holland made one (or even a USA one). Alternatively, I would go after the PSVANE CV-181 as the most magical sounding and highest resolution currently manufactured tube. Definitely as expensive as some of the Amperex, but you know you're getting a good tube.