While on the game map, the layered music plays really softly. So I turn up my speakers to hear it. Then when I go on the Kingdom Info screen, it gets MUCH louder and then I have to turn my speakers down, but then when I'm done with the kingdom screen, the music gets all soft again.
If I go back to the main menu (Esc) then that music plays all full volume as usual. I played the mp3s in Windows Media Player as a sanity check, and the volume was fine.
I don't know if debug.err will help, but it's linked.