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.
Would it be feasible to cathode-couple the bottom triodes of two SRPP amplifier stages? Kind of a long tailed pair, with the benefit of good linearity and low output impedance. I would use it as phase splitter driving a push-pull output stage.