Most Musical 6NS7 tube for a Preamp?

The best sounding 6SN7 I have tried in my Supratek Syrah preamp is the cheap Russian  military black base OTK.They are a bit microphonic however.They do sound very dynamic and vibrant though.The worst I have tried is the Shugyang Treasure CV181-Z which sounds quite muffled and dull.The USA Sylvania 6SN7GT black base is decent but a bit lifeless.What would be nice is something with the dynamics and vibrancy of the Russian military and the quietness of the others.Any suggestions.

By the way the Supratek is a fantastic sounding preamp.I own a Supratek Cabernet 300B as well.

A friend lent me a box of 6SN7s to try in my Supratek.

Most of the preferred older ones were there including the Ken Rad VT231,Brimar CV1988,RCA Grey etc .My pick was the Toshiba 6SN7 GB.The most neutral,open ,clean and detailed.Second was probably the Ken Rad VT231.What is best though probably comes down to your system.If you want a big meaty sound then the RCA Grey are like that.Some people say voluptuous.Not neutral though.