The first Conrad-Johnson amplifier, the MV75 came out in June of 1979. The snapshot here shows it with the optional front panel and tube cage. Using 6550 output tubes, the MV75 was rated at 75 Watts/channel or could be switched to mono operation at 150 Watts.
It introduced Conrad-Johnson built in bias indicator circuitry that has been a convenience feature on every Conrad-Johnson tube amplifier.