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100% degenerative feedback could eliminate. (Still, my bet is on local feedback. I just do not trust a global feedback loop that envelopes several gain stages. And I worry about the clipping behavior of the global feedback based amplifier. Yet I have heard such amplifiers sound good. More experimentation is needed.)
The circuit bellow is cathode referenced. The difference between this circuit and the unity-gain one is that inputs to the output device have been switched: the top device is driven from the plate and the bottom device is driven from the cathode.
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Pentode front-end with a resistor voltage divider
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Testing this front-end is easy enough: just ground the input and observe the noise on both outputs of the phase splitter. Should they differ in either phase or amplitude, the output stage will then treat the noise as signal to be amplified.
Split-Load Gain Circuits
Once again we have two variations to choose from: plate referenced or cathode referenced. In both cases we have an output stage that provides gain at the cost of a much higher output impedance and a greater distortion figure. In the previous examples the output devices functioned as followers, but as they are configured here, they function as either grounded cathode or source or emitter amplifiers. But more gain means more potential feedback, so what we really have is a zero-sum game, wherein the feedback can be applied locally or globally. Which is better? The global feedback network will provide a lower distortion figure. This is so because all the feedback can be used to iron out the most guilty device; whereas its own gain would set a lower limit to how much distortion
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Split-load, cathode-referenced, gain output stage
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The bottom device is obviously a grounded "something" amplifier. This is easy to see. But the top device also looks like it is functioning as a follower, as the output is taken at its cathode or source or emitter. The twist lies in the top device's input being referenced to the output and not ground. What difference does this make? Considered the what happens when the output is externally forced up 1 volt by a quick going pulse. When the top device is ground referenced, the pulse moves the cathode or source or emitter to become 1 volt less positive than its grid or gate or base.
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