Balanced Mosfet
I built some very simular with a Jet-Mosfet (toshiba-zetex) cascode front end. Then a IR610 follower and IR150 for the output
All current souces are Mosfets. Biased at 2.5 Amps in each leg.You really neeed to do offset at front end. You have to adjust the output cuurent sources have to move quite a bit to change offset. I have all the Fets matched and want the transconductance all thermal to match for lowest distortion and offset-temperature drift. I have Mosfet follows for all supplies and you only need one supply for the output stage. No coupling caps, servos, bipolars. Constant load on the supplies. This about the best Mosfet topology I have heard yet. No source resistors on output. Very stable since it has no global feedback. Excellent dynamic contrast, pitch stability, and resolution. Lot of tube attributes without the hassel other than the heat. A nice elegant easy to build and debug design. I really like haveing the filter caps out of the signal path! You could always put a tube front end on it........
H.H.