The orchestral part is of primary importance, evidenced from the first notes in a splendid rendition of the Prelude, which juxtaposes themes of the children’s prayer and the witch’s music. Act 2 (here played without a break from the opening scene) further showcased the orchestra, with the Witch’s Ride, forest music reminiscent of “Forest Murmurs” from Wagner’s Siegfried, and the great balletic pantomime that closes the act. The singers, all past and present members of Pittsburgh Opera’s resident artist program, were delightfully into their parts, individually and as a theatrical ensemble. Corrie Stallings, a lovely mezzo-soprano whose voice type puts her in line for lots of “trouser roles” (operatic teenaged boys) was totally convincing in gesture and demeanor as an awkward adolescent asserting his masculinity while desperately trying to conceal his fears. Ashley Fabian pranced around appealingly as his more sensible but nonetheless unpredictable sister, while Leah Heater (formerly Leah De Gruyl) and Craig Verm lent an element of pathos to the parents who cannot provide for their offspring. Marianne Cornetti, a Pittsburgh favorite who sings the big Wagner and Verdi parts all over the world, stole the show as the Witch, even though her character doesn’t sing until late in the opera. She has a formidable stage persona with voice to match. She was funny, forbidding and altogether riveting in conveying the evil glee of anticipating baking the youngsters into her dinner. The younger artists, however, struggled to be heard above the orchestra, even as somewhat reduced here, and kept in tight rein by the sensitive conductor. Ms. Fabian sang with clarity and accuracy, but her voice is not large enough for a theater of this size, and many of Gretel’s loveliest lines were lost in the fray. Ms. Stallings came through intermittently better, but the irresistible tunes of the opening scene dance duet, for one example, just didn’t have their intended effect. Ms. Heater and Mr. Verm both have solid, mature voices, but the Mother’s Act 1 solo turn demands more heft than this admirable mezzo could muster, although she conveyed convincingly the conflicting emotions. Mr. Verm brought verve and fervor to the feckless Father, but struggled with the highest notes that the role calls for. With her forceful, pungent soprano, Caitlin Gotimer had no problems being heard in the dual roles of the Sandman and the Dew Fairy – turning the Dew Fairy’s brief solo into an unexpected highlight.