In this case, my assignments would be writing stories or RP material. In that case, i choose what i listen to carefully, because the music will guide my work. For example, if i were to work on a project while listening to NIN, it would likely turn dark and tragic rather quickly. Likewise, if i were to tackle the same project while listening to Foster the People, it would likely have a more upbeat feel to it.
I just love that i can do my two favorite things at the same time, and make it a single activity.