As its main contribution to the Mozart-at-250 year, the Salzburg Festival is putting on all 22 of Mozart’s stage works, from pre-teen fragments to the last opera, “La Clemenza di Tito.” Mozart ended far too soon, of course, but “Tito” was a fine one to end on — an unqualified masterpiece. It is an opera seria, using a text by the poetic master of that form, Pietro Metastasio.

Metastasio is somewhat laughed at today, as formulaic and stodgy. But we learn something interesting from Rodney Bolt’s new biography of Lorenzo Da Ponte, the librettist of “Don Giovanni” and so on: Da Ponte revered Metastasio. And he wasn’t wrong.

When the Salzburg Festival premiered the Martin Kusÿej production of “Tito” in 2003, the cast was superlative. In fact, it would be hard to imagine a better Mozart lineup today. Four of the six cast members are back this year; the two who are missing are the soprano Barbara Bonney, who sang Servilia, and the young Latvian mezzo Elina Garanča, who sang Annio.

They have been replaced by two excellent, not-quite-famous singers: the Polish soprano Aleksandra Kurzak and the Swedish mezzo-soprano Malena Ernman. The Salzburg Festival is a great finder, or confirmer, of talent.

And, on Wednesday night in the Felsenreitschule, all six cast members – all six, not an exception — sang outstandingly. Look, sometimes the Festival really does live up to its reputation as the peak of the musical mountain.

Ms. Kurzak proved herself not only as a singer but as a singing actress, too. And the same is true of Ms. Ernman. She knew how to sing dramatically — emotionally, passionately — without violating Classical style.And it will be no hindrance to her career that she is beautiful to look at.

Portraying Vitellia, as in 2003, was the astounding soprano Dorothea Röschmann, and she was in top form: regal of voice, clean of technique, invincible. She rolled out a lower register that made her sound downright mezzo-y. In one aria, she sang a low G and a high B, with equal freedom. In fact, she sang a slew of high Bs (as “Tito” includes a lot of G major).And though she sings purely — always — she can provide some volume, too.

Our Sesto was, again, Vesselina Kasarova, the Bulgarian mezzo, with a dusky, plump, gorgeous voice. Plump as that voice is, it can really move, for Ms. Kasarova is a nimble singer. She is also a musical singer. The aria “Parto, parto” was unusually sly, and very effective. Ms. Kasarova was a touch flat in the second act, when the music was exposed — indeed, unaccompanied by the orchestra. But that was almost nothing.

At the end of the evening, when she came out for her solo bow, the audience made one of the loudest noises I have ever heard in an opera house.

Luca Pisaroni, the Italian baritone, was Publio, smooth and sure as always. And, in the title role, once again, was Michael Schade, the German-Canadian tenor.

I have run out of ways to praise Mr. Schade’s singing, particularly his Mozart singing, but let me mention this: It’s amazingly easy. I once heard Leontyne Price praise a singer by saying, “For you, it’s like falling off a log.” So it is for Mr. Schade, seemingly. In the Felsenreitschule, he displayed marvelous lyricism and complete technical control. And, theatrically, he was every inch the insanely clement Tito.

Doing a first-rate job in the pit was Nikolaus Harnoncourt, and that began with the overture, one of Mozart’s best. This music was both purposeful and springy, an excellent Mozartean combination. Throughout the opera, Mr. Harnoncourt was on fire, giving no evidence of fatigue from his exertions these past several weeks. (He is conducting “The Marriage of Figaro,” too.) The entire score had terrific character. And the Vienna Philharmonic was both glowing and incisive — another excellent combination.

I have not so far addressed the production, and that is, in part, because I issued my vituperations three summers ago. There are some new wrinkles this year. The little boys, in the first act, are in something like boxer shorts, instead of their tighty-whities. And at the end of the opera — when they’re being served up for human devouring — they are in long pants, instead of those ’03 skivvies.

What’s that line about gratitude for small favors?

A final word about the production: Before the terrorists’ explosion — this is during the assassination scene — someone yells out, “Achtung!” At least I believe I heard this. It’s curious, however, given that “Tito” is an Italian-language opera.

But once we start trying to analyze avant-garde opera productions, we head into the weeds. This I can tell you with confidence: Wednesday night’s “Clemenza di Tito” was a feat of Mozart singing, playing, and conducting, and the audience seemed to feel lucky to be there. It was.

Salzburg Festival until August 31 (for more information, call 011-43-662-8045-500).