Pass XA25?

M2(x) uses the voltage over the degeneration resistors as input for the autobias circuit based on the 4n35. Without degen resistors in the OPS, you would not have M2.

Yes, I can see that.......on schematic.....so we need a way to control bias without "degeneration".....

Then there should also be a good "sonic" reason to avoid degeneration.....like lower distortion, lower output impedance....larger class A envelope.....etc....