This article on Open Culture concerns one of my favorite writers, Philip K. Dick. In reading his Exegesis, I learned that we worked in a music store as a young man and he often listened to music while writing. The article contains a free Spotify list of some of his favorite classical pieces. I don't do Spotify, didn't even know what it was until today, but I'll be sure to check out some of these pieces.
Here's another good article with links to 33 of PKD's stories as free e-books.