Stephen Klein is a commanding personality, a man with stage presence. The imagination wants to give him a baton and an orchestra, or a spotlight and an audience -- the latter not all that farfetched a fantasy: Klein, 38, used to be an actor, and his resonant voice and buoyant personality could fill an auditorium.

The curtain calls, however, are years behind him, and any conducting Klein does is business -- conducted in a windowless office in the backstage labyrinth of the Kennedy Center. Klein is the new executive director of the National Symphony Orchestra.

From behind his desk -- a surface laden with the latest copy of High Fidelity magazine, a pack of Winston Lights, a coffee mug and warmer, a dozen black pens and an adding machine -- Klein watches, worries over and directs the NSO. He smokes. He bites his nails. He confides that he "has a lot of deep, dark, in-the-middle-of-the-night fears, because [an orchestra's] financial situation is rocky." He is as well versed in the argot of a corporate CEO as he is in that of the music-making NSO: Words like "budget," "adagio," "net" and "concerto" punctuate his rapid-fire, 12-hour days.

If a day in the life of Klein were set to music, it might bear a title like "Variations on the Theme of Committee," and it would almost certainly be an orchestral work replete with 16th notes and played molto vivace. "Development steering committee," "finance committee," "orchestra committee," "artistic advisory committee," "executive committee," "chamber music committee" -- each committee ultimately diminishing or augmenting the annual budget ($12.5 million for 1986) over which Klein presides.

The job of executive director for a major orchestra includes relationship building: meetings, breakfasts, midmorning croissants and coffee, luncheons, talk-back sessions, teas, cocktails, fundraisers, dinners with the likes of Catherine Shouse, Roger Stevens, Marta Istomin, congressmen, orchestra musicians, guest conductors, donors (potential and actual), board members (June Hechinger, Austin Kiplinger), other orchestra managers, volunteers -- whatever with whomever, in an effort "to be with and see the people with whom we have an association we want to strengthen," he says.

Klein falls occupationally and naturally into the glad-handing Washington scene. A boisterous conversationalist, he backs up his handshake or pat on the arm with a magnetic warmth. His bass-baritone voice slides as easily across a room filled with strangers as it does across a desk: "Hello. It's sooo nice to see you . . ." Yes, you believe, he means it.

"Stephen has to be all things to all men," says Virginia Mars, NSO president. Klein does not, she says, manage the orchestra from a distance. Before a rehearsal, for example, an orchestra member may want to talk -- about "anything," says Klein, "repertoire, a great conductor we should see as a potential guest conductor, a rehearsal that went a few minutes overtime . . ." Or there may be a problem "as mundane as parking in the tunnel and parking in the overall center." Or another musical dilemma, over finding a guest soloist, for instance: "We've got an artist, but the fee is outrageous," or, "It's great, the fee is okay, but the only thing he wants to play is one concerto that we did twice last year."

Klein struggles to keep a broad perspective and not, as he says, "get too locked into the detail of pencils." In the early stages of his orchestra management career (which began in 1977 at the Cleveland Orchestra), he was a detail man: "I had to be on top of absolutely everything. Every detail." By the time he was an orchestra manager for the Denver Symphony, detail wasn't his job, but the obsession with it continued: "I was walking around Denver at one point," Klein remembers, "talking about light bulbs." Tapping his head for comic effect, he smiles and asks, "Helllowww?"

But light bulb detail is seductively easy. Klein says "that was a natural thing, something I was comfortable with -- not light bulbs, but the immediacy. Okay: problem, immediate plan of action, immediate solution. When you try to look at the broad picture, you don't have that fast a plan of action or that fast a satisfaction.

"In that way, mowing the lawn is a very satisfactory thing. You do it. It's great and wonderful, and you have the immediate satisfaction of, ahhhh, a gorgeous lawn."

Now, says Klein, "I've got to see the whole damn forest."

In August, when Klein, his wife Mary and their two young children moved to Washington, NSO Music Director Mstislav (Slava) Rostropovich, in characteristic bear-hugging style, gave his new comrades a proper, Russian welcome. "We moved into our house on the 26th," Klein recalls. "The movers arrived at 8 a.m., and Slava was there ahead of them, to give us an icon, a samovar, a loaf of bread, some salt to put in the corner . . . to do a little blessing on our house, and to put our cat in the house for five minutes before we walked in, because that would chase away all the evil spirits. It was splendid. Just wonderful."

Fifteen minutes later, Rostropovich dashed off to catch an airplane, and two days later, like a quick study, Klein was off, as well, for the orchestra's five-week European tour. "I have these terrific guilt feelings about how that was for my family," Klein says. "Mary was up to her armpits in boxes all around the house, the kids didn't know where their schools were, the dog still hadn't found a favorite tree . . . And there I am, gone for weeks."

Those weeks, however, enabled Klein to develop a working relationship with Rostropovich, the musicians, the staff and members of the board. The musicians, in their first extended look at the new director, observed a hail-fellow-well-met manner embodied in a blue blazer, button-down oxford shirt, chinos and Weejuns. As one musician put it, Klein is "preppy -- in the nicest way."

Of his counterpart and new friend, Klein chants "Slava, Slava, Slava . . . I absolutely adore Slava. My family adores him. The kids love Slava; Slava loves the kids."

Klein nevertheless recognizes that given their jobs, he and Rostropovich "will come at cross-purposes on things. We already have. Slava's job, as music director, is to be in charge of the music of the organization. As executive director, I have to round off some of the hard edges, to look at things with an overall, business perspective . . . to see the whole thing. He has to look more at the artistic side. But we play off each other." And without abandoning their own convictions, Klein and Rostropovich find "not Path A or Path C, but a Path B that satisfies both of us," says Klein.

Klein didn't grow up with a burning desire to be an orchestra manager. He always loved the arts, "be they performing or curatorial," but the one art in particular was acting. "The idea first came to me when I was in about second grade. What I wanted to do, more than anything else, was be an acktahh," says Klein, flashing his Brooklyn accent.

He earned a bachelor of fine arts degree in theater from Boston University, toured with the National Shakespeare Company, and went one summer to Tanglewood to work as an acting coach for opera singers. ("I've always been a real opera freak," Klein explains.)

And then he went to New York to make the audition rounds. "I finally got a show that ended up consuming the next 18 months of my life": "Jesus Christ Superstar." Playing Caiaphas in "this insane musical was paying the bills pretty well," but Klein began to ask himself, "is there life beyond an 8 o'clock curtain?"

He grew discontented knowing where he would be every single night at exactly 8:22. "You find yourself out there emoting and doing things," says Klein, "and there is no contact with the brain. It's mechanical, and you are doing this thing, while in your mind you are going, 'Oh, I'm going to have to stop off and pick up some kitty litter and some bathroom tissue and some dish-washing liquid.' "

When his "Superstar" stint ended, he did "what a lot of entertainers do -- punt work. I was singing at -- I don't know if I want to tell you this -- Radio City Music Hall, for 12 or 14 weeks." During that period, however, Klein arranged to spend a week at an American Symphony Orchestra League seminar on orchestra management, and was "fascinated with the whole thing."

Perhaps the point of no return for the future orchestra manager came with the next move -- to Gates Mills, Ohio, back to his prep school, Hawken. Quite far from the New York arts scene, but quite near Cleveland and the Cleveland Orchestra. The school recruited him as both a teacher and director of its new arts-communication building, the latter role allowing him to develop booking and management muscles. The Cleveland Orchestra absorbed some of Klein's restless energy, allowing him to begin working with Lorin Maazel and other orchestra staff on a variety of narrating projects. They developed, for instance, a concert version of Beethoven's "Fidelio" interwoven with plot summary read by Klein for the summer festival at Blossom.

Meanwhile, after three years, the prep-school life was wearing thin. A lunch one day with the orchestra's general manager began with a plea for advice from Klein ("What am I going to do?") and concluded with the general manager picking up the tab and saying, "Consider this a job interview."

The interview must have gone well. Klein's first job at the Cleveland Orchestra was as an assistant to the general manager. By the time he left, five years later, he was orchestra manager.

He moved on to the top spot of the Denver Symphony. His work there sounds like a rehearsal for what he will have to accomplish in Washington: He started a summer-season festival, increased subscriptions, increased the donor base (to 7,500 from 2,000 in two years), balanced the budget for two out of three years. "Basically, I enjoyed it terrifically," he says.

He takes a slow drag on his cigarette and savors the feeling of his new role at the National Symphony: "Aaaaahh, this is okay stuff." He playfully adopts a pose of self-satisfied ease, but there's truth behind it. "It's a real pleasure. I can't say I am surprised, but I am really delighted," Klein affirms. "The orchestra's work is exceeding, I think, my hopeful expectations. Great Expectations. Dickens."

There's that actor, again, self-conscious and sportive.

Great expectations? Well, why not? After all, to Klein's mind, "the orchestra, beyond a doubt, is a world-class-caliber orchestra. I think we have to maintain that, strengthen that, and make it go, but we also have to notify others -- get everybody else to believe what we know is true . . . A lot of the factors are there, in place. We have to find something just to get the orchestra a little over the top, in the public's perception."