How did you replace it, Goa? Do tell. Me curious.
With a "music replacement mod" that is extremely easy to make.
A. This may or may not be necessary, but convert all of the music you want to use to .ogg format. There are many of free programs that can do this, but I used foobar2000.
B. Place them in a new folder called "Sound".
C. Go to your SoaSE root directory (with the .exes). There you will find the Sins sound folder.
D. In with the sound effects are all the music in the game, usually called say "Advent 1" or "Battle 5" etc., pretty much any file that's over 1000kb is music. Find any music you want to replace (Vasari # for example) and rename one of your .ogg tracks to that name. Continue until you've done replaced all the music you wish.
E. Go to your mod folder and make a new folder called "Music Replacement Mod". Put the sound folder with your recently renamed .ogg tracks there.
G. Enable the mod and now whenever the game would have played the track "Advent 1" or whatever, it will play the track with the same name in your mod folder.
As this mod has a checksum of 0 (you're just telling the game to load a different track basically), it can be used with any other mods or even multiplayer without problems.