audio amplifier

i have a an amplifier. But I don't know the circuit flow
of the diagram because it uses two Sziklai pair of transistors.

Q1 and 2 are pre drivers. Q3 and 4 are a push pull amp. In other words Q3 drives the positive side of the wave form and Q4 drives the negitive side of the wave.
Look here;
https://en.wikipedia.org/wiki/Sziklai_pair