The next circuit shows the last trick: noise cancellation. The potentiometer that serves as a cathode resistor for the bottom driver tube allows a small amount of negative power supply noise to be injected into the drive signal for the output tubes. Since the power supply noise enters at the cathode, it is not phase inverted at the plate. And because the negative power supply noise is out of phase with the positive power supply noise, the interjection of the negative noise will counter the positive noises influence on the output transformer's primary.
     How about the cathode follower configuration? Can a DC-coupled driver be made that functions as well as the amplifier version? Yes, one can be devised, but it requires an additional driver tube. The following circuit illustrates the DC coupling of the output tubes and, appearance to the contrary, this drive circuit realizes the same gain on each leg.

    The top output tube receives its drive signal from the cascode part of the of the driver stage. The bottom output tube, on the other hand, receives its drive signal from the generic grounded-cathode amplifier portion.  Although the topologies look different, both portions of the driver circuit deliver the same current gain. When this current gain is applied to the 62k plate resistor that attaches to the B+, the current yields the entire drive signal that the top output tube's grid will see. And when the current is applied to 62k plate resistor that attaches to the bottom output tube's plate, the current yields a drive signal that the bottom output tube's plate movement will undermine. If the bottom output tube sees a positive going input signal, its increased current conduction will pull its plate down, which in turn will pull down the input signal. This means that the bottom tube, like the top output tube, can never realize any voltage gain. But both output tubes do provide current gain, which the output transformer delivers into the load.
     Just how both bottom driver tubes manage to maintain an equal current gain is worth studying. Normally, a cascode will realize a much greater gain than the grounded-cathode amplifier. This is due to the cascode preserving much more of the triode's transconductance by preventing its plate voltage from falling. In this driver circuit, the cascode portion does not lock its bottom triode's plate at one voltage; instead, it applies the same voltage swing that the neighboring grounded-cathode amplifier's plate sees. This tracking is accomplished by attaching the cascode's top triode's grid to the grounded-cathode amplifier's plate. Thus, whatever transconductance the grounded-cathode amplifier loses, the cascoded bottom triode will also lose. What complicates seeing the interaction within the driver stage is the 100% degenerative feedback applied by terminating the grounded-cathode's plate resistor into the bottom output tube's plate (terminating this resistor into the B+ would be intuitively much easier to grasp).

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