Op amps are just simpler, but with some brain busting i think even a discrete design is within reason. It's just a project I want to take on for myself in my quest for knowledge, a good book was recommend as a starting point for learning to do this sort of stuff. FWIW the guys who actually build and design extremely high quality preamps are for the most part self taught mad scientist types who don't have engineering degrees, it's just math and trial and error.