Greetings! It is possible, yes, and quite simple.
As Mark said (I wrote up a post but you beat me to it
![Wink ;)](https://forums.geshl2.com/Smileys/classic/wink.gif)
) just go to said folder to edit out the desired file of said level.
Make sure your mp3 files go in Steam\steamapps\sourcemods\gesource\sound\music.
As far as I know, any bitrate will work.