Do you master your music yourself ?

Mixing and mastering is a sepparate skill in the process of making music and equalizes the track's loudness, relationships between instruments and voices in the mix for easy listening. I can do this just fine with own creations that I make. If however someone I work with would like to send their tracks to another engineer that is just fine and I can send them the sepparated audiotracks that form the musical piece so they can send it over for mixing to their desired engineer.