Hespèrion XXI has been played over 10 times on NTS, first on 24 January 2019. Hespèrion XXI's music has been featured on 15 episodes.

Hespèrion XXI is an international early music ensemble. The group was formed in Basel, Switzerland in 1974 as Hespèrion XX by Spanish musical director Jordi Savall (bowed string instruments, particularly the viola da gamba), Montserrat Figueras (soprano), Lorenzo Alpert (flute, percussion), and Hopkinson Smith (plucked string instruments). The ensemble is noted for its scholarship in early music — especially the music of 16th and 17th century Spain. Their performance practice is noted for the liberal use of improvisation around the basic melodic and rhythmic structures of the early pieces, resulting in great emotional intimacy and immediacy.