(!!!!!) (Best Pair 1950's) 7N7 Sylvania chrome top NOS 1956-1957 1-3% matched (8/9ma and 8.6/8.4ma) (best 6SN7 sub using adapter sockets)
(!!!!) (2nd Best Pair) 6EW7 Hitachi Japan branded Westinghouse BIG BOTTLE NOS 1970-1972 (5.8/6.1ma and 58/62ma)
(!!!!) (Best Pair #2) 7N7 Sylvania branded RCA and Sylvania NOS 1960-1963 (9.4/9.0ma and 9.6/9.8ma) (High Gm) 1-5% matched
(!!!!) (Best Pair #3) 7N7 Sylvania branded RCA 1960 era (8.4/8.4ma and 8.6/8.8ma) 1-3% matched
(!!!!) (Best Pair #3) 7N7 Sylvania branded RCA amd Sylvania 1960 era (8.4/9.5ma and 8.6/9.8ma) (same Gm) 1-3% matched
(!!!!) (Best Pair) 6EW7 Hitachi Japan branded Westinghouse BIG BOTTLE NOS 1970-1972 (5.5/5.2ma and 52/56ma)
(!!!!) (Best Pair) 7N7 Sylvania branded RCA 1960 era (10.4/10ma and 10.6/9.8ma) (High Gm) 1-3% matched (strong pair)
(!!!!) (Recommended Pair) 6EW7 Hitachi Japan branded Westinghouse BIG BOTTLE NOS 1970-1972 (4.9/4.6ma and 42/43ma)
(!!!!) (Recommended Pair) 7N7 Sylvania branded GE chrome top NOS 1954-1956 (7.4/7.0ma and 7.4/7.2ma) 1-2% matched
(!!!) (2nd Best Pair) 6EW7 Hitachi Japan branded Westinghouse BIG BOTTLE NOS 1970-1971 (4.9/5.2ma and 59/56ma)
(!!!) (Recommended Pair) 7N7 Sylvania NOS branded GE and RCA 1960-1965 (9.4/8.0ma and 8.0/8.4ma) (close Gm)
(!!) (Best Single) 7N7 Sylvania branded Philco NOS parallel black plates 1940's (7.5/7.9ma)
(!!) (Pair) 6S4A GE NOS 1969-1970 (24.0ma and 25.5ma)
(!!) (Recommended PAIR) 6S4A RCA USA black plate NOS 1960's - 1970's (25.5ma and 28.5ma) (Highest mA and Gm)
(!!) (Recommended Pair) 6S4A Westinghouse black plate NOS -1963 era (20ma and 21.2ma)
(!!) 7N7 Sylvania branded Philco used/good short bottle parallel gray plates 1948 (7.2/7.6ma)
(!!) 7N7 Sylvania NOS 1960's (8.6/10.2ma)
(!) (Best Single) 7N7 Sylvania NOS 1960 era (10.8/11.2ma)
(!) (Good Single) 7N7 Sylvania branded GE NOS 1961-1962 (7.5/8.3ma)
(!) (SINGLE) 7N7 Sylvania TALL BOTTLE branded Hytron parallel black plates chrome top NOS 1952 - small chip/blemish at top of tube (7.6/7.8ma)
