Stage 1 = Class A Common Collector
Stage 2 = Class A Common Emitter
Stage 3 = Class B Complementary Symmetry (Crossover Distortion)
Fix crossover distortion by increasing resistance of pot biasing Q3/Q4 to 2K ohms. This makes the 3rd stage a Class AB.
AI = 210.5
AV = 2
AP = 421
