I own Cary CAD300 sei and replaced Sophia's 6SN7 right away for many NOS, which are, imo, way better in many ways.
On the other hand, lots of folks swear by them, but to me, Chinese made tubes aren't even close to an good NOS, especially at the price of USD100 each, crazy, if you ask me.
To name a few: GE5692 Brown base, Sylvania VT231, Sylvania 6SN7W, Fivre 6SN7 or Tung Sols Black coated glass round plates, Sylvania Chrome coated ( not just top, but the one that covers the glass lower to the base, but even Chrome top only will do good job ), ECC33 Mullard Brown base, Brimar CV1988.
Some of above are more expensive than others, but Sylvania, in general, made lots of very good sounding tubes and can be hit for a very nice price if you shop around.
On the other hand, lots of folks swear by them, but to me, Chinese made tubes aren't even close to an good NOS, especially at the price of USD100 each, crazy, if you ask me.
To name a few: GE5692 Brown base, Sylvania VT231, Sylvania 6SN7W, Fivre 6SN7 or Tung Sols Black coated glass round plates, Sylvania Chrome coated ( not just top, but the one that covers the glass lower to the base, but even Chrome top only will do good job ), ECC33 Mullard Brown base, Brimar CV1988.
Some of above are more expensive than others, but Sylvania, in general, made lots of very good sounding tubes and can be hit for a very nice price if you shop around.