Let me answer from the synthesis perspective - which is one of my main
interests. Learning to design new synthesisers is a pretty dark art, and
most of the books/resources I found take a very theory-centric stance which
I found to not be particularly useful.
However, I have found the following practical guides extremely
Each of these has a slightly different take on walking you through the
practicalities of synthesis design inviting you to actually build your own,
experiment and play.