Excellent article, Herb. The reference to the Beatles production and engineering is especially noteworthy. Initially, their producer, George Martin, had only TWO tracks to work with. By '63 he had four tracks to work with and the genius he applied to such a limitation is detailed in his book "All You Need Is Ears".
Chapter 8, "Layering the Cake" goes into detail about the nuts and bolts of the recording process he used. It's a pretty amazing documentary that every aspiring engineer and producer should read. In Martin's case, less HAD to be MORE...it was all he had. There are tons of other tips and tricks and gear he used, presented in the book. Also a treasure trove of Beatles trivia and minutiae. Check it out.
~Rob
Amazon: ISBN 978-0312114824 $14.99
All You Need Is Ears - George Martin