i just followed that link provided by Tamren, it was saying something about installing bonus pack v1.05
but i thought, what the hell, if it downgrades ill just update again via impulse
but then i logged in and everything and it said file not found?
whats it supposed to do/be Tamren?
anyway, in relation to the topic, a music selector would be nice, but i think Sins dynamic music player would prevent choosing your own music.
that is, if you zoom into a GW with a battle where you are winning, Sins would probably be playing a winning track, whereas if you zoom in on another GW where you are losing the battle it will play a trouble track. alternatively, if there are no battles, or if you zoom all the way out, it will play a quiet track. (these are just arbitrary names taken from the sound folder where Sins stores all the music, which, btw, i have copied and use WinAmp to play, omg, so happy)
all that means is that choosing your own music would be contrary to what we have now. IC probably put alot of effort into their dynamic music player, so they might be a little less than enthusiastic to enable you to choose your own music... considering the current system is deisgned to heighten the experience.
i personally would love one, there are definitly some tracks i like more than others, however i dont see it happening 
on a seperate note, i noticed there are some music files contained in the Souns folder that never occur in the game? TEC3 and TEC4 are a few examples. if you download WinAmp or VLC to play you will see what i mean. any ideas? maybe they were thrown in for the benefit of later x-packs?