Warren, I'm not familiar with your SEP-1 preamp. I tried to do some research on it in the threads, but not much info. Here's an interesting thread:
http://db.audioasylum.com/cgi/m.mpl?forum=tubes&n=51757&highlight=sep-1&r=&session=
As I understand it, this preamp was designed to use two 6DJ8 tubes, the lowest in the line of this type family. I was going to recommend my favorite 6922 version the incomparable Siemens CCa, early 60's, grey plate, but they're very expensive. What matters is what you like. If the Tungsram sounds good to you, then enjoy it in your preamp. Tube rolling can be fun, but frustrating at times. I finally found what works best in my preamp and have stopped the tube rolling and began to stock-pile a few pairs for the future. Apparently there was a SEP-2 version where one owner liked a pair of early Amperex 6922 pinched waists. Have fun experimenting and Merry Christmas.
