The 40 members of the Princeton Pianists Ensemble prove that the piano isn’t always a solo instrument or accompaniment: Some pieces feature 10 performers at once. The group, shown above at its annual “Piano Extravaganza” in McAlpin Hall, will play during Communiversity April 17. To view a performance of the Danse Infernale and the Finale from Stravinsky’s “Firebird Suite,” go to paw.princeton.edu.