I have a friend who has the ability to try many many different tubes in his Dodd battery pre.
I was at his house a month ago and we compared the tubes that I have (amperex Orange) with his favorite...Seiman Gold pins (9622?)from the 1950's.... The Seimans did everything right and allowed more emotion to come through. More decay in the notes, more air around instruments etc..
I finally got a pair from him and immeadiately put them in. Holy smokes, it made even more of a difference in my system than I heard in his.
This is a great upgrade. Highest recomendation if you can find them.