The original soundtrack was made using the WAV file format, since this is how the music artist made the music tracks. The same format was used by the voice actor(s). This is the initial format. However, there are 2 problems: this format is compressed and not compatible with MSU, plus the tracks don't loop. This is why the conversion into PCM was necessary, plus the tracks needed to be made to loop correctly. This was done by a different person than the once who made the music and it is a complex process, which means the initial WAV files would do the end user no good, unless if he just wants to listen to music tracks outside of the game and with no looping.