I haven't met anyone else like this as yet, but I'm always dreaming of music. I would sing or even make beats in my dreams and hear everything as clear as ever. In fact, dream music sounds warmer in my head and its not directional unless you're singing it. Its like its coming from all around you but there is no interference or change in amplitude. Here's a song I actually wrote about a dream where I heard a beat based on some samples I had laying around: https://soundcloud.com/underminded/02-surreal-songs-ft-ozzy
My head somehow chose those guitar samples I heard so long ago and turned it into a beat...so when I woke up I dug for hours trying to find it and I recreated it.