Hans Werner Henze is a classical composer who brings a passion for political radicalism to much of his work. Although his political-musical activism really took off in the 1960s, he developed a deep hatred of fascism in his youth while growing up in Nazi Germany. He left Germany for Italy in the 1950s, out of a sense of frustration with German homophobia. The premiere of his oratorio, The Raft of the Medusa, in 1968 occasioned a riot when students took the work's dedication to Che Guevara as license to hang a red flag on the conductor's podium and the musicians objected. He writes music that combines a lyrical beauty and avant-garde techniques. Most of the music of his on Youtube is not explicitly political.
To start off with actual "night music," a nocturne: Symphony #1, Movement 2, "Notturno" (1947)
Lucy Escott Variations (1963)
Prison Song (1971) Inspired by the prison diaries of Ho Chi Minh
Ein Kleines Potpourri (2000) (Themes from his opera Boulevard Solitude)