We've enhancement the proofing gallery by providing a flash-based slideshow with your own choice of music!
You will need to first upload your music library under Proofing Gallery module, Music Library menu.
Then when you create/update a gallery, simply select the desired music for that gallery from the music drop-down list. That's it. The music will be playing in the background of the slideshow. It can be manually started/stopped by click on the button on the top right corner.