What is interesting is how some components are sensitive to different tubes and some are not. For instance, I have a Tubes4HiFi SP-14 that reacts strongly to going from say a Sylvania to a RCA to a Russian 6SN7. Not that any seem bad, just you are well aware of the change. Something is different like Coke vs Pepsi.
My K&K Maxxed-Out phono stage has 2 6DJ8 types. Kevin voices it for a Russian 6N23P which is equivalent to a 6922 (another 6DJ8 variant). Well I bought a couple of hundred dollars worth of 7308s, 6922s and 6DJ8s figuring if the lowly Russkie tube sounded good, the fancy pants ones must sound better. Nope! The stock tubes were the most dynamic with just the right amount of bite, hight end sparkle and a tight grip on the bass notes. I did find I preferred a Russian "Rocket" logo 6N23P slightly over what Kevin supplied and they were a whopping $45 a pair. The "better" tubes were too laid back with the vocal receding into the mix too much.
My little Wright Sound WLA-12a hardly cares which tube it is playing with. It is somewhere between the 2 above examples. I like it best with the staggered backplate 6SN7s but can't complain about the Sylvanias or the Russian metal-based equivalent that are supposed to be the cat's meow. Whatever is warmed-up and glowing is fine in the little fellow. You can hear a difference but it is slight.