Well, since tubes only come in N-Channel flavor, how this solid-state topology going to be transformed into a tube circuit equivalent? While exact topological translation is impossible, functional translation is. Our aim is to have a small, linear driver tube directly augment the output stage's output, while simultaneously driving and correcting the less-linear, beefy output tubes. The Circlotron push-pull circuit makes use of only N-Channel tubes because of horizontal layout of the circuit. Had there been P-Channel tube, the Circlotron push-pull probably would never have been created, as the totem pole configuration as used in the Futterman amplifier would use complementary N and P-Channel tubes in the same fashion as N and P-Channel transistors or MOSFETs are used solid-state output stages. This same horizontal layout of the circuit of the Circlotron allows us to cross-couple the small tubes to the large tubes.
    The circuit shown below uses the 6DJ8 triodes to receive the input signals. If the output does not follow their cathodes, their cathode-to-grid voltage will change in value as a consequence.

   A change in cathode-to-grid voltage causes a change in current flow through the triodes, which results in a correction signal to the opposing 6AS7. Why is this worthwhile? The big problem with any tube OTL amplifier is output impedance. In the absence of feedback, the tube's relatively high plate resistance preclude a low output impedance. 4-8 ohms is typical in the 6AS7 based amplifiers. This is outrageously high, as even a zero feedback 300B single-ended amplifier has a much lower output impedance. While a super low output impedance is of doubtful worth, anything over 1 ohm is problematic, as un-tunes tuned speakers, such as bass reflex boxes. 
   So what this circuit does is apply a quick, short feedback loop across the 6AS7s. This feedback greatly reduces the output impedance and lowers the distortion of the amplifier. But isn't all feedback bad? Well, if all feedback is bad, then the 300B must be bad, as the triode's rp effectively applies a small feedback loop across the tube. Cautiously review all absolute statements, including this one.