If you really want to learn about great amps, I highly recommend researching and building one. Watch the Burning Amp lectures. Read Nelson Pass's wealth of articles. I'm anything but an electronics engineer, but my understanding of amps has come light-years in the course of researching, building, and troubleshooting a Pass amp. Pass has dozens of designs that he's written articles on and explains well. Bob Cordell explains some older circuits well too.