Rare Matched Pair Mullard KB/DA CV492 ECC83 Valves NOS I61 B1G5 Codes (V2)

Both have Matching I61 B1G5 Blackburn Codes. Rare Matched Pair 12AX7 ECC83 CV492 Valves/Tubes.

Book Spec = Ia 1.2 - Gm 1.6. Valve 2 Ia 1.9/1.9 - Gm 1.95/1.9. Valve 1 Ia 1.8/1.75 - Gm 1.85/2.