For changing the music without renaming mp3 files, this is possible, but I wouldn't recommend it if you don't have modding experience for this game.
For some clubs like the asylum, the music is coded in the map file (.bsp). Then you have to edit the path for the music object using the vpk tools.
For other clubs, the music path is coded in the sound schemes. The problem here is that most of these are not unpacked from the archives in Wesps patches, so you have to find and unpack them yourself.
So it's probably easier just to create a \backup subdirectory in \music\licenced, move the original sound files there, and then copy in your soundfiles using the names of the original files.
But whatever you do, make sure not to use anything that contains additional information created by the windows media player as this will crash the game. Mp3s with more than 256 kbps also can cause trouble.
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