SPICE simulation of a very high quality BJTs power amplifier in class A. Three stages, class A amplifier, double simmetrical differential couple with current mirrors. Sources currents with automatic control of the constant current amplitude. Feedback circuit and couple of compensation capacitors for every differential couple of the first stage. Darlington and cascode configuration transistors in the intermediate stage. Complementary parallel final transistors in emitter follower configuration, and SOAR circuit with double slope limiter circuit.