Well, the posted Alctron MA-1 schematic certainly has at least one error! The idents of Q3 and Q4 are reversed.?
As Jerry has surmised, the cascode amplifier inverts the signal.
I can confirm that the signal present at the drain of Q2 is connected to pin 3 on the MA.1 pcb, and in the inverse polarity of the signal present on pin 2 of the input.
So the polarity of the signal is reversed by the device.... which is presuambly why the output connections are reversed?
