From creating mini-masterpieces of music for cellphones to collaborating with Chicago’s only contemporary art music cassette tape label, Spektral Quartet has established themselves as some of the most unique and imaginative voices in classical music. Now, the string quartet is working with accordionist Julien Labro to introduce American audiences to a largely-unheard corner of new South American classical music. They are playing Wednesday at City Winery with Labro for their CD release show, but first stop by Morning Shift to share some music.