Read this thread with interest. I do not use any Modwright equipment but I do have a Supratek preamp. which also uses 6sn7's and is also tube rectified. After some tube rolling with 6sn7's which include BT,-very musical and smooth, but lasted only 3 months, had to return them-, Sylvanias short bottles -nothing special-, RCA's grey glass very smooth and musical, kind of floppy bass, RCA gtb kind of the same, Sylvania 5692's black base, very rare, the real thing w/ additional rods and micas, -kind of cold sounding, don't think are really suited for this preamp. I really like a Raytheon short bottle -it is very musical dynamic and balanced, some microphone- Sophia Electric -having a lot of fun with these, much better experience than w/ the BT's. And lastly, -heresy!- I always come back to my trusty EH's and TS's reissues...... Across the board, they seem to have all the good qualities of all the above tubes. I can pick up things other tubes do better but these are the most balanced. And why? I strongly believe that Mick Maloney, Supratek's designer, voiced his designs with modern manufactured Russian 6sn7's and both the EH's and TS's meet this requirement. In private communications he has hinted to this. I guess Mr. Wright has his favorite 6sn7 tube to voice his designs but maybe it is not the most expensive and most "NOS" tube out there, would be good to find out. This has been my experience with my preamplifier so far and my 2 cents. And, for the rectifier I am using the Bendix 6106- have to get another GZ34 though my Mullard is not well lately.....another story