Barrington Stage Company offers a take on the Sondheim-Wheeler classic highlighted by performances in shades of regret.PITTSFIELD, Mass. — I thought I’d seen everything you could do with “A Little Night Music,” the nearly unimprovable 1973 musical by Stephen Sondheim and Hugh Wheeler. But Barrington Stage Company’s bittersweet revival, which opened here on Wednesday, ends the first act with an especially deft touch. As the principals step forward for the final chorus of “A Weekend in the Country,” envisioning their upcoming visit to a grand estate, each carries a revealing and slightly absurd item of personal luggage.Count Carl-Magnus Malcom, a military peacock, has a gigantic hunting bow slung over his shoulder, the better to stalk game or romantic rivals. Anne Egerman, an 18-year-old virgin married to Fredrik, a stuffy middle-aged widower, totes a bird cage. (She’s the canary.) Fredrik’s son, Henrik, struggling to reconcile his seminary ethics with his hots for his stepmom, clutches a prayer book. And Fredrik himself, perhaps not realizing he’s bringing skoals to Newcastle, bears a neatly wrapped and ribboned bottle of champagne.“A Little Night Music” is like that champagne; when the original Broadway production opened, Clive Barnes, in The Times, called it Dom Pérignon. Bubbly it certainly is, especially Wheeler’s ingenious book, based on the 1955 Ingmar Bergman movie “Smiles of a Summer Night.” Henrik loves Anne; Anne won’t sleep with Fredrik; Fredrik longs for the actress Desiree Armfeldt; Desiree is kept by the jealous count; the count’s wife, Charlotte, is desperate for his attention — round it goes.And even though the stage is set for what could be a tragedy (guns do come out), when they all meet for that weekend at the manse of Desiree’s mother, it ends as happily as a Shakespeare comedy — on the surface. The mismatched and damaged souls get repaired, in both senses of the word.Despite that effervescence, though, “A Little Night Music,” in any half decent production, is also about rue. That’s even more salient in this first year following the death of Sondheim, who layered its brilliant songs so densely with varieties of regret. We feel that regret doubly now; for the characters no less than for us, pleasure is always coupled with loss.So perhaps it’s no surprise that this Barrington Stage production, directed by Julianne Boyd, gets the rue so right. Especially in the performances of three of its central women, mixed emotion is always palpable. As the embittered Charlotte, Sierra Boggess offers a sad and hilarious sketch of a wife so steeped in the brine of her own disappointment that she actually looks pickled. And Madame Armfeldt, Desiree’s imperious mother, is no senile narcissist in Mary Beth Peil’s vivid performance; she’s a woman clinging as hard as she can, in her final days, to the thrill of a fully lived past.But it’s Emily Skinner as Desiree, the focus of the complex romantic geometry, who most powerfully holds the show’s opposing forces in equilibrium and produces its warmest glow. She’s funny, of course; the scene in which she welcomes Fredrik (Jason Danieley) to her apartment after a performance and, despite his paeans to Anne, consents to revive their long-ago liaison — “What are old friends for?” — is a model of perfectly played situational humor.Later, though, the humor deepens. Near the end of the weekend, when Desiree realizes that her last-ditch dream of getting Fredrik back for good has failed, Skinner offers a reading of the show’s big hit, “Send in the Clowns,” that, aside from being wonderfully sung, is as layered as a lasagna. Beneath her good-sport bravado is anger — at Fredrik, to be sure, for still being “in midair” when she’s “at last on the ground.” But beneath that is something unexpected and even richer: anger at herself for having failed to care in time about the squalid carelessness of a tossed-off, footloose life.Vocally, the production is exceptional, with Danieley a standout among singers including Cooper Grodin as the count, Sabina Collazo as Anne and Sophie Mings as Anne’s randy maid Petra. (She scores big with “The Miller’s Son” — a showstopper but, given to a minor character, perhaps the work’s one misstep.) Every word sung is perfectly clear (the sound is by Leon Rothenberg), and the ensemble moments are gorgeous, almost overwhelming in the relatively intimate theater.Still, on opening night, there was much that needed fine-tuning. Lighting cues went awry, scene changes were erratically paced, wet clothes didn’t drip and a shattered glass produced no sound. More substantially, the men were not yet digging as deep as the women. Danieley’s Fredrik, not stiff enough at the start, has little to unravel as the evening’s profound events bear down. And Noah Wolfe’s Henrik is so floridly agonized that it’s hard to see how his profoundness may yet be appealing.A weekend in the country, with, from left, Sierra Boggess, Cooper Grodin, Jason Danieley, Sabina Collazo, Noah Wolfe and Sophie Mings. Daniel RaderSuch problems will most likely take care of themselves before the show closes on Aug. 28. There’s nothing to be done, though, about the weak-tea watercolor set by Yoon Bae and the odd costumes by Sara Jean Tosetti. (For “Send in the Clowns,” Skinner wears a gold brocade gown with lamé sleeves that looks more like a 1970s Vegas castoff than Sweden in 1900.) And though the reduction of Jonathan Tunick’s original sumptuous orchestrations to a string quartet, two keyboards and one overtaxed reed player is sufficient to support the show’s more intimate moments, the high-spirited ones lack their Straussian oomph.These are among the costs of putting on a very ambitious show at a regional theater without big Broadway money behind it. In that sense, they may be not just the costs but also the glory. It is, after all, no small thing to be able to see such worthy productions — and I’ve seen many here over the years — in a ragged, deindustrialized city like this one. It’s crucial to the culture that complex work be performed creditably at every level, and crucial to the local economy too. Barrington Stage appears to be one of Pittsfield’s most successful concerns.For that, you have to thank Boyd, who along with Susan Sperber established the company in 1995 and will retire as its artistic director at the end of this season. (Alan Paul takes over in October.) Having directed “A Little Night Music” once before, in 1998, when the company performed in the auditorium of a high school arts center in nearby Sheffield, she knows all about its mixed emotions: how the promise of growth and the acceptance of limitation are often the same thing. That’s the gift she brings to the stage at the end of Act I — just as she has brought it, for 28 seasons, to us in audience.A Little Night MusicThrough Aug. 28 at the Boyd-Quinson Stage, Pittsfield, Mass.; barringtonstageco.org. Running time: 2 hours 40 minutes. More