In a grounded cathode amplifier, the gain can never exceed the mu of the triode. But in a cascode, this limitation disappears. For example a 12AU7 based cascode circuit can have a final gain of 260, if the Ra is large enough (1 meg).
    Now in the horizontal version of the cascode, the first triode is also locked in a voltage vise grip by virtue of its plate connecting to a power supply that is terminated into the cathode of the second triode, whose grid is literally grounded. Yet voltage variations at the grid of the first tube will result in current variations through the tube, which in turn will snake their way through the second power supply into the second tube and then into the third power supply and then into plate resistor, which leads back to the first power supply and then the first triode again. To safely experiment with this topology, replace the plate resistor and all the triodes with 1k resistors and replace all the power supplies with 1.5 volt batteries. Now measure all the voltage relationships throughout the circuit.

Split-Load Phase Splitter
    The split-load phase splitter is a variation on the grounded cathode amplifier that stipulates equal values for the cathode resistor and plate resistor. Both resistors are AC grounded at one end and output is taken from the other end. 

   Before going horizontal, let us do a little mind stretching. Moving the ground reference point to the top of the circuit leaves the circuit functionally unchanged in terms of gain, output impedance, and PSRR, but it does alter the voltage relationships, as the grid is now at -200 volts. And both load resistors remain AC grounded at one end, which is a necessary condition for this circuit to work.

   Where else can we move the ground reference point while still keeping to a single power supply? Two possibilities present themselves: either slide both the plate and cathode resistors together below or above the triode and connect the ground to the midpoint.

    In the circuit above, the outputs are taken at the ends of the both load resistors. But how are two phases possible? As the triode conducts lesser or greater current, the resistors experience lesser or greater voltage across their leads, much like an accordion contracting and expanding.

Generic split -load phase splitter


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