Dennis Kastrup was born in Bielefeld in 1976 and grew up there. After spending time abroad in the United States, he graduated from the Marienschule der Ursulinen. This was followed by community service in Bethel and several semesters at the universities of Bielefeld, Detmold, and Paderborn. During this time, he developed a passion for music, which led Kastrup to the local campus radio station Hertz 87.9, where he spent three years, ultimately becoming music editor-in-chief. In 2003, he moved to Berlin and gained his first experience for public radio at radioeins. Over the decades, Kastrup worked for various radio stations and magazines. Today, he commutes between Berlin and Montréal.