Hybrid Power Amplifier Using 12AX7 as Input Stage and VAS, 2SK1058 - 2SJ162 as Current Buffer

In this days I'm working around an Hybrid Power Amplifer
Below the Microcap Simulation Schematic

M2 and M2 are Hitachi 2SK1058 Mosfet
M3 and M4 are Hitachi 2SJ162 Mosfet

Bias current is around 100mA

V1 and V5 are High Voltage Supply, around 300Vdc
V3 and V4 are 50Vc for Power Stage

X4 is TL071 Op Amp used to fix to 0Vdc the ampli's voltage offset.

The Negative Feedback Network is present

X3 is a SRPP as Input Stage
X1-X2 are used as VAS and to drive the Power Mos Stage