TAD KT66 Quartet(4pcs) Premium Selected valves. The TAD KT66 delivers old-school tone out of the box. Legendary tone know by Plexi-Marshall JTM45 and JTM45/100 Amps and now in den all new Modern-Vintage Amps 2266 and 2466. Remake of the great British KT66 as known by MOV (MO Valve), GEC, Genalex and Gold Lion. This tube made Marshall JTM45 Plexi Amps famous in the 60's and the Quad HiFi amps a legend. SRV used the KT66 to his Fender amps for his outrageous guitar sound. Replaces 6L6GC and 5881. With the QUAD HiFi power amps the KT66 gained reputation as a great tube for High Fidelity and the TAD KT66 is first choice for the QUAD II Classic amps made today.