Hi,

What is the difference between complementary and quasi compementary Class AB output stages?

Thanks

 

You can find out in Google.

A complementary output stage uses comlementary output transistors. One NPN and one PNP.
A quasi-complementary output stage used two NPN output transistors and a little NPN and PNP driver stage because a long time ago power PNP transistors were very expensive or not available.