Thank you, it worked:)
It turned out to be a veeery stupid question because after compiling it even shows you what to do.
Although I had in mind making a ready .tun file to work with my code without the need of loading in it musicbox for recompilation, but I guess that doesn't even make sense because of different start addresses...

EDIT:
So for sound effects I have to make a couple of small "tunes" and use xxxx+0 to choose between them, right?
But if I wanted to have music always playing and share one channel of music with sound effects?
Would I need two musicbox players code? with the effects' one having priority over the music player?