Teach me everything you know, OP. :-D
I played bass for 17 years, never did any recordings myself, but I'm really into audio as a result.
My weird solitary hobby is probably doing mythological and folklore cross-reference work, and trying to arrange the bulk of it chronologically to the best of my ability to do so. It plays a substantial role in the side-by-side of the evolution of ancient civilization all the way up to the development of Monotheism, which is why I find it so interesting. Much of ancient mythology and folklore is actually shaped by lunar/solar events, which also ties into the Milky Way and Space which are also things I study as a hobby. It's honestly mostly something I enjoy doing as a sort of therapeutic, after work practice.