I'm a hobby guitar amp builder who likes learning the circuits as well.The second half of a long tail pair inverter is the grounded grid amplifier.The grid of this section is grounded through a capacitor.I have read this establishes an AC ground to the grid.I guess I'm not getting how that pertains to this circuit.I know a capacitor can bypass AC components of fluctuating DC current around a resistor.I understand most of how this circuit works in a basic way.Exactly what is going on here?Thanks.