E-Mail This Article to a Friend Clemency Prism Opera delivers medium-rare Mozart BY LLOYD SCHWARTZ

Prism Opera is a game little chamber opera outfit that over the past few years has offered impressive and imaginative performances of important but neglected works. Last week at Pine Manor College’s Ellsworth Hall, Prism director Thomas Stumpf gathered a cast of notable Boston singers and Timothy Merton’s superb Sarasa Chamber Music Ensemble in a production of Mozart’s La clemenza di Tito (which Stumpf translates as "The Magnanimity of Titus"), the last opera Mozart began — he started work on it after he embarked on Die Zauberflöte, but finished it quickly before returning to his final operatic masterpiece.

Popular in its time (though it seems that at the premiere in Prague, Empress Maria Luisa called it "una porcheria tedesca" — a pile of German pig crap), it virtually disappeared until the mid-20th-century. Bostonians have had opportunities to hear it from Boston Lyric Opera and Monadnock Music, both productions with the thrilling Mozart soprano Elisabeth Phinney, from the BU Opera Program, and from the Handel and Haydn Society, with Lorraine Hunt Lieberson and Jeanne Ommerle towering above a mediocre cast and Christopher Hogwood providing bouncy-bouncy conducting.

The reason for its disappearance is clear. Mozart was going back to an older form of opera, "opera seria" ("serious opera"), a stilted genre in which characters enter, sing, then leave. Mozart mastered the form early, in Idomeneo, then dropped it for a more flexible and engaging kind of operatic dramaturgy. Still, this outmoded form inspired some great music — hence the revivals. Based on a pre-existing libretto by Pietro Metastasio that Mozart’s collaborator, Caterino Mazzolà, pared down, the story concerns the legendary benevolence of the Emperor Titus. By the end of the opera, Tito (as he’s called in Italian) even forgives Sesto, the friend who has tried to assassinate him. Tito understands that Sesto’s betrayal was prompted by his infatuation with Vitellia, the real schemer behind the coup — the angry daughter of the king whom Tito’s father deposed.

The greatest music in the opera is a series of arias, accompanied recitatives, ensembles, and choruses at the end of act one. In the magnificent "Parto, parto" ("I’m going, I’m going"), Sesto (a marvelous role for mezzo-soprano Pamela Dellal, who stole the show) finally agrees to Vitellia’s plan to murder the king. No sooner does he rush off than Vitellia (soprano Susan Trout, whose snideness was a source of much of the production’s energy and humor) learns that Tito has just decided to make her his queen. In a spectacular trio, in which the music rises and falls simultaneously, Vitellia is torn between joy and terror. She’s finally getting the throne, but it’s too late to call Sesto back. The act ends with Sesto’s apparently successful assassination of Tito and a choral ensemble of tragic grandeur.

Prism director Stumpf is an operatic Orson Welles. He not only staged and designed the production, and conducted from the fortepiano, he also made his own English translation and replaced the dry recitatives (not composed by Mozart) with spoken dialogue. This helped move the action forward by placing the focus where it belonged, on the music. The translation was lucid though without much poetry, and sometimes comically flat. ("Vitellia, what are you doing here?") After an energetic overture that benefitted no little from the authoritative rhythms of John Grimes’s timpani, Stumpf’s conducting began to sag. There were disconnects between stage and pit. Singers waited too long to pick up their cues, so many of the gains in pacing were lost.

Stumpf’s staging was minimal and fluid but missed the mark in a couple of places. Vitellia tried to stop Sesto by calling after him in the direction opposite from the one he had just raced off in. After the failed coup, Annio (elegantly sung by mezzo-soprano Krista Rivers) tries to get Sesto to explain matters to Tito: "Go to him," Annio encouraged Sesto, but he was looking away from his friend.

The role of Tito is tricky. It needs both tenderness and power, so that Tito’s magnanimity doesn’t seem just goody-goody. Arthur Rishi has a light lyric tenor voice that went awry on only one high note, but his softness triggered more giggles than awe. Young Briana Rossi, a Northwestern University junior already on her way to an international career, was a lovely Servilia (Sesto’s sister). Bass-baritone Paul Guttry made Tito’s dignified minister more blustery than Mozart intended.

The ideal Vitellia should be as sympathetic as appalling, trapped by her hatred and at least partly in love with Sesto as she uses him to further her ends. Susan Trout perhaps overemphasized Vitellia’s ruthlessness. She’s an exciting singer because she always goes for the jugular, but she doesn’t always hit the richest vein. As Sesto, Dellal combined her usual sympathetic presence and vocal warmth with masterful coloratura technique.

The eight-voice chorus was strong and engaged. The parched acoustics of Ellsworth Hall’s bear pit of a stage did no one any favors, though it was a great night for clarinettist/basset-horn player Diane Heffner, who seemed born to perform Mozart’s gorgeous obbligati.