Wolf Trap, to many, denotes commercial pop at the Filene Center. But the Wolf Trap Opera is a different animal: a tiny, can-do opera company focused not on presenting big stars but on cultivating future ones. In Wolf Trap’s 40 years, singers from this company have colonized the opera world as artists and administrators. A raft of them returned to the Filene Center on Wednesday for a gala concert, the highlight of Wolf Trap’s 40th anniversary, of a type and caliber even the Kennedy Center hasn’t offered for years. The singers care so much about the place they even donated their services.

Certainly grooming stars is a tough and unpredictable business; an artist can work his or her heart out and still not have the star wattage that inflames an audience. It’s hard to criticize an artist for being earnest, eager and admirable, as are many of the singers on the first half of Wolf Trap’s program; but this first half was also a reminder of the fact that there are fewer and fewer opera singers today who really excite the public.

Denyce Graves, who sang “Acerba volutta” from Cilea’s “Adriana Lecouvreur,” stood out: Her tone production and intonation were erratic, but her voice is undeniably imposing, and she has a genuine stage presence and spark. Tracy Dahl, by contrast, who joined her in the duet from Delibes’s “Lakme” that’s been achingly overused in films and TV commercials, was the quintessential perky American soprano, working her heart out in one of the sleepwalking scenes from Bellini’s “La sonnambula.” Even the usually fine Emily Pulley was a little pale in Rusalka’s “Song to the Moon” from Dvorak’s opera. One wondered if Wolf Trap’s distracting amplification — which here, as in “Sweeney Todd” earlier this summer, had a way of changing levels while people were singing — put singers a little off their feed.

Oren Gradus offered a blustery turn as Mephistopheles from Gounod’s “Faust,” only approximately in contact with the pitches; Matt Boehler was subdued in Rossini’s comic chestnut “La calunnia”; the veteran Richard Paul Fink offered an honorable but slightly tarnished prologue from Leoncavallo’s “Pagliacci”; and Robert Orth, the elder statesman of the night, had a lot of fun with the shtick of Gilbert and Sullivan in “I am the very model of a model major-general.”

But the evening, it turned out, was only warming up, and there were plenty of reminders ahead that a young artist’s earnestness can sometimes transform into insouciance and/or magnificence. Tenor Lawrence Brownlee, his foot encased in a white orthopedic boot, offered a little of both in the famously fiendish “Pour mon ame” from Donizetti’s “Daughter of the Regiment,” its high C’s sounding beautiful, easy, and not even all that high, and even — gasp — like fun. He later showed equal flowing ease and beauty in the duet from Bizet’s “The Pearl Fishers,” with Fink as a worthy partner.

Then there was Mary Dunleavy, whose shining, secure beauty of voice in Verdi’s “La traviata” evoked Golden Age greatness. I have a pet theory that any soprano who is actually able to get through the difficult cabaletta “Sempre libera” is bound to sing it terrifically; Dunleavy certainly did (despite almost being hijacked by the careless orchestra at one point; Stephen Lord, who conducted the whole evening with remarkable stamina, managed to restore order).

Also evoking past greatness was a quartet from Verdi’s “Rigoletto,” and not only because it was a staple excerpt in the days of 78 recordings. Tenor James Valenti has grown deeper and richer and warmer of voice since last I heard him. The one fly in the ointment is a nervous top register, which he doesn’t command with the same authority he brings to his low notes; it’s a significant “but” for a tenor, but he makes a fine sound. His fullness, Dunleavy’s sweet silver, Fink’s robustness and Graves’s big, full chest notes combined to sound old-school in the best sense.

Eric Owens, though currently a hot operatic property, hasn’t quite yet inhabited the role of King Philip (in Verdi’s “Don Carlo”); he sang expertly but with a slightly careful quality. Alan Held, however, is clearly in his prime. Having closed the program’s first half as Wagner’s Wotan, guiding the gods into Valhalla, he came out on the second half to make a star turn out of Leporello’s catalogue aria from “Don Giovanni,” using an iPad in place of the usual scroll or sheaf of paper to demonstrate the number of lovers his master has had around Europe.

A happy sign of passing the torch was the fine showing by this year’s young artists, who made big impressions with their small contributions. Earlier this summer, I speculated that the mammoth title role of Offenbach’s “Tales of Hoffmann” was too much to ask of a young tenor such as Nathaniel Peake. Hearing how terrific he sounded in the excerpts he sang Wednesday, I could certainly understand why he had been cast in it. The evening ended with all the alumni — those who have gone on to run companies, as well as those who sing in them — joining in the final fugue from Verdi’s “Falstaff” and then capping the evening with “Let Our Garden Grow” from Bernstein’s “Candide:” a fine end to a celebration that gave everyone reason to celebrate.