Mosfet

THD 1khz 1W 8ohm 0.000541%

THD 1khz 100W 4ohm 0.026%

Damping factor 100hz / 1khz = 8/((20.705*8)/20.656-8)= 421

I decrease the supply voltage on VAS to reduce dissipation to be able to use TO92

Simple current feedback like F5 or amazing circlotron (PASS)

Ltspice file

Thanks to Joseph Norman Berry who offered me a solution for voltage stage :

THD 1K 28V 4ohm (100w) 0.0027%

THD 1K 4V 8ohm (1w) 0.0001%

Need to change VAS CCS for thermal compensation.

Ltspice file

THD 1K 28V 4ohm (100w)  0.002729%
THD 1K 4V 8ohm (1w) 0.000105%

450mA @20°C
300mA @40°C
150mA @ 70°C

Ltspice file

The amazing fet circlotron with differential current feedback and CSS

Ltspice file

OPA604 Circlotron with diamond Buffer

Ltspice file

OPA604 Circlotron with OPA Buffer

Ltspice file

Ltspice file