I have a question about relative voltages and operating points of components, in this case tubes. Are these two functionally the same? For a while now I never could understand how the bottom triode of the WCF in an amp I bought was biased at -100v on the grid and 0 volt on the plate which would put the tube way into cutoff. It just dawned on me that since the cathode is -75v then 0v is effectively +75v on the load line for the triode and -100v is actually -20v. It then occurred to me that if 0v = +75v as far as the triode is concerned then can high positive voltages relative to other parts of the amplifier be considered low voltages in the WCF? For example the picture on the left, to each triode the relative voltages are the same as the voltages on the right. Does this mean that they would both function the same? In this case is 170v on the output of the left picture effectively the same as 0v to a speaker I hook up to it? (Assuming the other end of the speaker is also 170V) Or perhaps if I connected the picture on the left directly to a 150v input stage would it still be considered the same as the picture on the right as far as the tubes are concerned?