Well, there can be life after director Eric D. Schaeffer for the house that Stephen Sondheim built at Signature Theatre. Frank Lombardi’s lovingly conceived, exquisitely sung A Little Night Music establishes that, while Schaeffer’s hand on the artistic controls may have created a signature for Signature’s Sondheim shows, strokes by other hands needn’t seem forgeries by comparison. There was some nervousness about that.

Schaeffer’s the guy who put this once-tiny Arlington company on the map by radically reconsidering works many found difficult and perplexing placing the audience onstage amid the gore in Sweeney Todd, moving Assassins from a shooting gallery to an art gallery, and heating up the passions in Passion to the point that the New York Times declared Signature’s production superior to the Broadway original. When Arena Stage wanted to revive Sondheim’s Sunday in the Park with George a season ago, Schaeffer’s presence was deemed so essential that the two theaters ended up co-producing the show.

But with the director jetting off to stage ever-grander musicals in Chicago and Manhattan, commercial road companies of Big and Oliver!, and an L.A. production of Putting It Together with Carol Burnett, Signature’s Sondheim franchise was clearly going to need some backup directors if it was to remain viable.

So Lombardi (Schaeffer’s assistant on last season’s The Fix) was the choice, and while he’s hardly breaking new ground with Night Music, he’s made the 1973 Tony-winner sing gracefully and with enormous polish.

The show’s plot, based on Ingmar Bergman’s Smiles of a Summer Night, has to do with the couplings and uncouplings of six romantically linked characters, three of whom are introduced in the opening scene: Fredrik (John Herrera), a middle-aged lawyer; Anne (Stephanie Waters), the naive 18-year-old he’s married in an attempt to recapture his youth; and Henrik (Robb McKindles), Fredrik’s son by a previous marriage, who’s madly in love with his new stepmother. By the time their three moody opening solos “Now,” “Soon,” and “Later” have blended into an enchantingly glorious trio, you know everything you’ll need to know about the evening’s intricate method and giddy sophistication.

Complicating the already complex relationships in this household are Desiree (Patricia Pearce Gentry), a celebrated actress who once had an affair with Fredrik; Carl-Magnus (Christopher Flint), Desiree’s current peacock of a lover; and Charlotte (Donna Migliaccio), his acid-tongued, long-suffering wife, who is also Anne’s confidante. A weekend outing in which all of them descend on the country estate of Desiree’s imperious mother (Ilona Dulaski) turns into the sort of farce that would set every available door slamming if Lou Stancari’s grandly designed classical patio had any doors.

Night Music’s music is among Sondheim’s most accessible, which is not to suggest it’s simple. There are interlocking melodies, and ravishingly complex trios, quartets, and octets, not to mention the waltz-time doodlings of a five-member chorus that pops into and out of the action whenever a scene needs to dissolve gracefully or one set of characters needs to be linked to another. For all practical purposes, the show is an operetta with especially dazzling lyrics, but that description doesn’t begin to suggest the heady nature of the authors’ civilized, endlessly inventive ruminations on infidelity.

Actually, I’ve misplaced an apostrophe in that sentence. Librettist Hugh Wheeler isn’t in Sondheim’s league when it comes to sophisticated repartee, so it’s only one author who’s being endlessly inventive. Except for an uproarious, insult-laced postprandial argument in the second act, Wheeler’s book scenes never come close to matching the songs’ cleverness of phrasing. But when a show’s lyrics contain as many tricky interior rhymes (“indiscriminate, women it…”) as this one’s do, it would be churlish to quibble too much about the interstitial bits.

The performers are all pretty splendid, but let’s single out a few, anyway. McKindles, looking and sounding a bit like Radar as that character might have been played in some 18th-century Scandinavian version of M*A*S*H, makes a hilariously conflicted Henrik, and as the blithely oblivious object of his desire, Waters, a Columbia, Md., high school senior, is fetching and in genuinely glorious voice.

Gentry’s delicately actorish way with Desiree’s one-liners is just right, and her handling of “Send in the Clowns” the score’s (and indeed Sondheim’s) only pop hit is lovely. And it would be hard to overstate the contributions of Migliaccio, whose caustic delivery of Charlotte’s zingers is as telling as are her finely modulated renditions of the character’s dark songs. A gifted physical comedian, she also makes hay with a killer of a sight gag involving a pair of scissors and some flowers. If the music weren’t building to a rip-roaring first-act finale at that precise moment, the audience’s laughter would stop the show in its tracks.

Lombardi’s handsome staging doesn’t quite make sense of that omnipresent quintet that keeps commenting vocally on the action, but it features elegant tux-and-ball-gown costuming by Anne Kennedy evocatively dappled by Jonathan Blandin’s lighting, and it makes full use of Stancari’s asymmetrical setting, with its closet-concealing pediments and balustraded platform for Jon Kalbfleisch’s orchestra. The stage, though shallow, is nearly as broad as that of the National Theatre which means the production feels enormous in a 136-seat auditorium, where no seat is farther than five rows from the footlights.

It also feels intimate, which is as much a matter of playing style as of distance from the performers. As has been the case with all of Signature’s Sondheim shows (except Sunday in the Park With George, which was staged at Arena’s 500-seat Kreeger Theater), the show benefits tremendously from being performed without vocal amplification. For audiences who’ve forgotten how effective a voice can be when it doesn’t have to travel through circuitry before reaching the ear, A Little Night Music will seem downright revelatory.

Not for Signature’s regular audience, however at least not aurally since the company has accustomed its subscribers to a pretty high level of musical performance in its eight-year history. Nor for Sondheim aficionados, for whom this Night Music will simply be a waltz down memory lane, not the vivid, life-changing experience Passion was. Still, let’s acknowledge that we’re in rarefied territory here. It’s not with every company, after all, that one has the luxury of responding, “Ho hum…just another fabulous Sondheim show.”

So many sideways glances and skittish pauses have greeted the name Bull McCabe by the time that stocky gentleman makes his appearance in The Field that you figure actor Robert Leembruggen will have to enter with six-shooters blazing if he wants to live up to his character’s advance billing.

My gunslinger imagery, I should note, is all wrong for Keegan Theatre’s often poetic, surprisingly suspenseful mounting of a play set in 1960s Ireland. But it’s the first that occurs to me because, while playwright John B. Keane hasn’t set his land-grab drama in our own wild West, he’s working with all the ingredients of a classic horse opera.

There’s the saloon setting, where hard-drinking locals flirt with the barmaid-with-a-heart-of-gold. There’s the kindly widder-woman who needs a good price for her acreage, and the fair-but-frightened auctioneer who knows the tight-fisted land baron will ruin him if the bidding goes too high. Bring on that snarling land baron followed by his vicious son, then bring on the straight-arrow city-slicker who’s looking to buy a spread for his wife (and who doesn’t appreciate the land’s loamy richness, only its access to water), and you’ve basically got any of a hundred episodes of Bonanza.

Except that the moment Bull McCabe starts to describe the field in question, talking shamrocks and cow dung, and letting us hear how well he knows every thistle that grows there, the evening acquires a dimension most westerns don’t possess. The Bull, as he is not-at-all-affectionately known by cowering locals, is definitely a bully and a social monster, but he is also, in his misguided, sometimes criminally overbearing way, a spokesman for the little guy. Skeptical of all laws, which he sees as favoring the professional classes, he’s become a law unto himself. And if he’s enriched those four acres by grazing his cattle there for years, he doesn’t see why any sane man would suggest he should have to part with it.

The fact that the city slicker who’s bidding against him has lived abroad for 20 years in an England that’s viewed by everyone in the play as an occupying power, and the idea that he wants to pave over part of the land further inflame the Bull. “I won’t be wronged in my own country,” he declares, setting up a situation in which he’ll instead do wrong in his own country.

Morally, he’s indefensible, but dramatically, he’s an intriguingly vivid character (as viewers of Jim Sheridan’s 1990 film starring Richard Harris will recall), and with Leembruggen scowling and growling, and everyone else on stage shrinking from him in Mark A. Rhea’s forceful staging, the evening acquires a certain melodramatic punch.

Which is not to suggest that the production makes particularly good use of the resources at its disposal. The Field is Keegan Theatre’s first production at Gunston’s Theatre II, and the troupe makes the same mistake there that every company initially does: Confronted with an enormous amount of stage space, it tries to use all of it and ends up placing the chief playing areas at too great a distance from the audience. The result is an intimate, conversational staging that doesn’t feel intimate at all. George Lucas’ set design, featuring a mountain road that climbs the back wall of the stage and a realistic Irish pub, is working way too hard, while Jenifer Deal’s costumes, which suggest social distinctions between the presumably impoverished McCabe family and their equally impoverished neighbors, don’t work hard enough.

Still, the performances (accents aside) are mostly capable, with Jeremy Beck’s skulking bully, Amy McWilliams’ nervously sharp-tongued mom, and Andrew Thayer’s feverishly placating barkeep all up to Leembruggen’s level. Things get a bit uneven around the edges, but that’s to be expected with a young company. To the troupe’s credit, for all the evening’s minor flaws, the story they’re telling is never less than taut and compelling.CP