Charles, a minor correction to your characteristically sage post. I'm pretty sure that the 211FE is a push-pull amplifier, not a parallel SET. I say that because it is described as transitioning from class A to class AB and then to class B at high power levels (a SET would always operate in class A), and also because it is described as being a "fully differentially balanced" design.
Best regards,
-- Al
Best regards,
-- Al