The bottom-gettered VT-231 Sylvanias(JAN-CHS) and Ken-Rads(JAN-CKR), from the Forties are wonderfully clean and airy, and present a wide sound stage(if the rest of the system supports). No artificial warmth, though some are fond of that. Not too pricey, either! If your amps take two 6SN7s each, mix them to get the strengths of both brands. ie: https://www.ebay.com/bhp/sylvania-6sn7gt and https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR2.TRC1.A0.H0.Xken-rad++v... This may be of interest: http://www.dehavillandhifi.com/6sn7_vt.htm I’ve tried the top fifteen tubes/brands, on that list. To me, all sounded to warm/colored, but the Sylvanias, Ken-Rads and Tung-Sols. I’m currently using a pair of 6SN7W(tall bottle/metal base) Sylvanias and a pair of Tung-Sol VT-231, round plates. Glad I bought a few pair, before the prices on NOS tubes went nuts.
