Replacing the transformer with tube circuitry requires adding at least two more tubes, if gain is desired. The circuits above show the three sub-circuits needed to make the amplifier. The first circuit provides the voltage gain; the second, the phase splitting; and the last the push-pull output stage. This is not the only possible array of sub-circuits, as a differential input stage would provide both voltage gain and phase splitting, as shown below.       

    The above amplifier reconfigures the transformer's grounding arrangements so that the amplifier functions as a pair of cathode followers in parallel with the load impedance.  Once again, the transformer provides voltage gain and phase splitting. The added 1-meg resistors and capacitors provide referencing connections to ground for the top secondary winding and to the output for the bottom secondary winding.

Beginning at the end
    As has been mentioned in this journal many times before, when we design a power amplifier, we must design backwards. We start at the load impedance and move back to the output stage and from there to the driver and input stages. Let's assume that the load is 32-ohms. The next step is to decide if the output stage will function as grounded-cathode amplifiers or as cathode followers. The big mistake many make here is to be fooled by appearances; just because the load attaches at the cathode does not necessarily mean that the circuit is a cathode follower, just as the load attaching to the plate does not necessarily mean that the circuit is a grounded cathode amplifier. (Maybe if the Input, Ground, and Output, IGO, circuit naming convention I have argued for in this journal had universal adoption, this mistake would be harder to make, as the grounded-cathode amplifier would go by the name of GKP and the cathode follower, by GPK, allowing a more relational viewpoint.)

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