Stephen Costello, left, as Nemorino, Ailyn Pérez as Adina, and Simone Alberghini as Sergeant Belcore. (Scott Suchman for WNO)

Pity opera buffa. To those of us who love opera, it’s delightful and melodious and frothy and fun, and Donizetti’s “L’elisir d’amore” is among its frothiest and funnest representatives. To those who don’t, it’s an acquired taste; it requires a certain suspension of disbelief to accept that these hackneyed, century-old jokes, all conveyed in music, are entertaining rather than simply dated. These latter often include younger singers who, not born to this tradition, do their best to immerse themselves in it, with mixed success.

The Washington National ­Opera brought back its “Elisir” on Tuesday night, and it did its level best to sparkle. Stephen Lawless’s serviceable production, set — like Bartlett Sher’s far more recent version at the Metropolitan ­Opera — in a gigantic barn, was a backdrop for the real-life lovers at the heart of the cast: the ­husband-and-wife team of ­Stephen Costello and Ailyn Pérez as the lovable bumpkin Nemorino and the beautiful, flirtatious but good-hearted Adina. Costello and Pérez sang very well and even started to seem, as they worked their way into the show, like they were having fun.

They didn’t have a lot of help from the orchestra pit, where the earnestness that seems to be epidemic among younger opera musicians seized the baton of Ward Stare, the conductor making his WNO debut, like oobleck. There was little fizz or charm in Stare’s rendering, just a lot of intensity, focus on romantic passages, and what seemed like a continual series of minor struggles to coordinate the orchestra with what was going on onstage.

This made it tough for the singers to take flight, particularly Simone Alberghini as Belcore, the egocentric military officer who comes lumbering into town with his troops and flatters himself that he’s made a conquest of Adina. Alberghini’s voice lumbered, too, in the general vicinity of the right notes. That he was capable of slightly more was evident in the duet when he signs up Nemorino for military service; Lawless’s direction called for him to do cancan dances with his soldiers, and his voice took on some corresponding agility.

The title’s “Elixir” is purveyed by the quack doctor Dulcamara, who is the opera buffa antecedent of Frank Morgan’s Wizard of Oz: a relic of another age, slightly larger than life even in his failure. Nicola Ulvieri has a fine, firm, flexible bass voice; what this character really needs, though, is character, and that he displayed only patchily. The mellifluous Shantelle Przybylo made much of the usually forgettable role of Giannetta; more, please.

Ailyn Pérez, left, as Adina and Stephen Costello as Nemorino. (Scott Suchman for WNO)

Still, there was no doubt that Costello and Pérez were the vocal stars. At first, Pérez seemed to hold the upper edge with a rounded soprano, light yet full, even displaying a touch of the limpid quality characteristic of old-school singers. Costello, by contrast, tends ever so slightly to bleat. But he makes an honorable sound, his notes are in line, and this role allowed him to shine in a way that last month’s “Moby-Dick,” in which he also acquitted himself beautifully, did not.

The two principals in this ­opera have unequal advantages: The soprano has the longer and tougher sing, but the tenor gets to sing “Una furtiva lagrima,” one of the most beloved arias in the repertoire. Costello did it very well, singing now gently, now ardently, and he was greeted with the warmest applause of the night. Pérez, by this point, had a lot of singing behind her, including at least one ensemble in Act II, just before her duet with Dulcamara, that’s often cut and that I, for one, was glad to hear. But she did tend to wander slightly sharp, and then slightly flat, as she tired, and didn’t always deliver the impact at the ends of her (tricky) phrases.

Still, both singers are a considerable cut above the norm, and they delivered a fine performance — enough, certainly, to enchant those who are already susceptible to opera buffa’s charms.

The Elixir of Love

continues through March 29, with two different casts, at the Kennedy Center Opera House.