A piercing whistle punctuates the blaring of a trumpet. But in the columned central space of the Fundació Antoni Tàpies, the only visible instrument is a grand piano. For three days a week throughout the course of the exhibition, the instrument is played—and, one could say, worn—by a pianist who stands in a hole cut into its center. Leaning over the rim of the piano to strike the keys, the performer energetically interprets the fourth movement of Ludwig van Beethoven’s Symphony No. 9 (1824), while slowly pushing the wheeled instrument around the space. The building has become a musical box, the exhibition orchestrated so that one movement flows into the other, spilling through the gallery’s spaces to create a dissonant soundscape. The piano of Stop, Repair, Prepare: Variations on Ode to Joy for a Prepared Piano (2008) could be thought of as the lead performer of Puerto Rico-based duo Allora & Calzadilla’s show. Popularly known as “Ode to Joy,” Beethoven’s piece has often been interpreted as a defense or celebration of humanist values, and in 1985 the European Union adopted it as its official anthem. Yet, as Slavoj Žižek has noted, the tune’s “universal adaptability” has made it vulnerable to use …