At first glance, combining organ and piano seems almost impossible: the piano's crisp, percussive attack and the organ's slow, sustained tone occupy very different acoustic worlds. Yet a surprising number of twentieth-century composers rose to this challenge. Marcel Dupré's three pieces – Ballade Op.30, Variations sur deux thèmes Op.35 and Sinfonia Op.42 – trace a journey from a near-concerto relationship to full integration. César Franck's Prélude, Fugue et Variation appears in the composer's own version for orgue expressif and piano. Sigfrid Karg-Elert contributes intimate character pieces for harmonium and piano from his Silhouetten and Poesien collections. And Flor Peeters' Concerto for Organ and Piano provides a rousing three-movement conclusion. Together these works make a compelling case for one of music's most unlikely partnerships.