“Twelve singers of three sexes, men, women and castrati will suffice for its execution,” Rossini wrote on the title page for his exceedingly curious Petite Messe Solennelle, “that is, eight for the choir, four soloists, in all twelve cherubim.” The composer had retired from opera more than 30 years prior, settling in Paris and gourmandizing on the beef tenderloin medallions topped with foie gras, truffle, and a Madeira demi-glace that epicures know as Tournedos Rossini. On the musical front, the composer turned out delectable pages he called his péchés de vieillesse, 14 albums worth of vocal, chamber, and solo piano pieces. Of these, the “Little Solemn Mass” is the last. But “petite”? Depending on tempi, its duration of an hour and a half (give or take) is neck-and-neck with Beethoven’s mighty Missa Solemnis. The conductor for the Edinburgh concert is Thomas Quasthoff—the same Thomas Quasthoff who defied devastating birth defects to forge a career as a star baritone in worldwide demand for Bach, Mozart, and Mahler, not to mention his passion for covering the hits of Frank Sinatra. If Rossini has never previously figured in Quasthoff’s repertoire, what of that? Ever-new departures are the artist’s way. Of his dozen cherubim, presumably excluding castrati, we know only that they are “gifted students.” —Matthew Gurewitsch