Well, it doesn't load the music from the server. Sith spit, that would take hours for 56ks.
Just create a folder in the base directory and rename it to "music". You don't need pk3s at all.
The path should be "music\mp\duel.mp3" and not "mp\music\duel.mp3".
If you use .pk3 files, you should take into account that the game does load them in alphabetical order.
Gidion, a.k.a. Dalboz
Take this, Jedi! Oh, no. What am I saying!