Well, someone educate me... The schematic shows 3k to 3.5k impedance? for the primary side of the output transformer. Should the transformer we're looking for be in the same range? It seems to me if your going to use one with a 200 ohm impedance, its looking like way too much of a load. Correct of not? Unless the output transformer is IN the circuit and it just needs a matching transformer.... but when, then, did the 600 ohm become standard?