WTF unbiased observation is a myth

So somewhere in the signal path there exists a resistor that's not on the original wiring diagram. What I think this does is changes the resistance in order to accommodate for whatever the output of the JJ tubes is.
ok but they must have also added a bias circuit if the amp is bias-able, you can bypass that
 
I'm unbiased when evaluating competitive samples. I have to be. Wouldn't want any field failures.