"Do your amps use one or two 6SN7 tubes ? I am confused about that" As I stated: I’ve been using 1940s, Tung-Sol(round plate/JAN CTL/VT-231) and Sylvania (6SN7W/JAN CHS/tall bottle/metal base) tubes, in my monoblocks for a couple decades(one each per amp). Yes, that’s one JAN CHS and one JAN CTL("one each per amp"), at the same time. I collected a couple pair of the metal base and a couple pair of the slightly later(sans metal), tall bottle 6SN7Ws(which to me seem equivalent), before either became so rare. If you’d read the observations, contained in the 6SN7 comparison article, the author mentions the following: "It appears combining tubes like the VT-231s as voltage amplifiers and 6SN7Ws or 6SNGTA/GTBs as driver tubes you gain the strengths of all. Using one type seems to accentuate the tube’s weaknesses." I’ve found my Sylvanias very faithfully pass("well balanced") whatever information I feed them(including the bottom-gettered VT-231s). I chose my favs, based on my preference for tubes that don’t editorialize. They all(Sylvanias, Tung-Sols and Ken-Rads) also passed more ambient information, resulting in a wider/deeper sound stage, than any of the others I tried. Happy listening!