Dover, thanks for the link to the transformer information. That was very informative. It is probably a little like finding out how sausages are made though. One part of the picture lost is the problems created if you dont use transformers. The alternatives have a lot of issues and problems too. One time at NASA I tried to find a linear capacitor. That was hard to find. I would think that isolation would be a very significant advantage of transformers, especially in a preamp.
Bob
Bob