• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

valve input stage and driver/phase inverter coupling

Of course push-pull drive to a diff amp is ideal, but these circuits both lack that.
Many tube amplifiers have had similar circuitry, including the Marantz Model 8B and 9,
so good performance is possible with such a topology.


Please forgive me - my comment was wrong, based on a too-hasty misreading of the schematic. I'm often wrong, but seldom so foolishly. (As if....)


All good fortune,
Chris