No disrespect meant to the people who work on the background music/sound of Brink, but after a while it tends to get old based on my an others' personal opinions. Sony isn't allowed to implement custom soundtracks (MP3 songs of your choosing to play during game play) due to some legal issues, so it's up to the individual games to release that feature as a work around if they want to include that. I find with some games after I've played them a while I like to listen to my own music rather then the same old sounds, That causes a disadvantage for some games Shooters in particular. This would of course be fine if custom sound tracks were implemented.
I as I'm sure others would greatly appreciate it if you added this on the release or as an update.