When you use the two buttons that toggle sound and music in the game play area, the sound one toggles both sound and music, and the music one does only music, which makes it impossible to just listen to the music.
As an extension, I would like a sound volume slider for sound only, and one for music, so I could set the levels to whatever I wanted.
I see your problem , but for now ,
you might want try the option button and see if you can turn up the music volum there ,
might help a little bit =P