Guest conductor Donald Runnicles proved adept at drawing a warmth out of the National Symphony Orchestra that made its lack of precision less irritating. (Simon Pauly/Simon Pauly)

When an orchestra has a new music director, the audience’s focus tends to be on how it sounds with him. When an orchestra is in the market for a new music director, the focus shifts subtly to how it sounds with guest conductors. So the fact that the National Symphony Orchestra began its regular season Thursday night under Donald Runnicles, who had never led the orchestra before, rather than its music director, Christoph Eschenbach, who will step down in 2017, was cause to prick up the ears — particularly since Runnicles made it sound so good.

You never know how a conductor will interact with a given orchestra. Runnicles, 60, is no newcomer; he was for 15 years the music director of the San Francisco Opera, and is still principal guest conductor of the Atlanta Symphony Orchestra, music director of the Deutsche Oper Berlin and chief conductor of the BBC Scottish Symphony Orchestra. But I wouldn’t have predicted, from my prior impressions of him as a competent but not necessarily vibrant conductor, that he’d have the stuff to bring the NSO to heel.

What most intrigued me about Runnicles’s performance is that he made the NSO’s weaknesses into strengths — starting from the very first chords. Thanks partly to the challenging acoustics of the Kennedy Center, the NSO specializes in fractured, ragged entrances; the last time I heard the orchestra play Mozart’s “Magic Flute” overture, its opening notes set a sorry tone for the evening. Runnicles, though, led these chords with buoyant assurance, striking not so much for being exact as for being emphatically present, round and robust. This wasn’t finicky Mozart, but hale, hearty Mozart, less focused on Mozart “style” than on imbuing the music with life and warmth, in such a way that precision, or its lack, wasn’t really relevant.

Runnicles’s other emphasis, for an evening that included Richard Strauss’s “Four Last Songs” and two Elgar works, the “Serenade for String Orchestra” and the “Enigma Variations,” was on balance. The NSO under Eschenbach has often had a hard time finding the right relationships between different groups of instruments so that the brass, say, sounds proportional to the strings without drowning them out. Runnicles had a way of holding out a chord, not static but slightly shifting, like a pulsing, living organism, until it finally, elegantly reached its own limits. Those first “Magic Flute” chords had space around them to breathe. You could hear the same kind of space in the protracted and ultimately eloquent end of the final Strauss song, “Im Abendrot” (“At Sunset”), and time and again in the kaleidoscopically colorful patterns of the “Enigma” variations, which were lively and engrossing entertainment.

The evening’s other debutante was the soprano Olga Peretyatko, a rising international star who made a memorable impression in Bellini’s “I Puritani” at the Metropolitan Opera last year. A “Puritani” singer isn’t necessarily a Strauss one, and you could argue that Peretyatko’s silvery wire of a voice, though it extended down to a cavernous lower register, sometimes paled in areas, like the second song, “September,” that called for more size and resonance in the middle of the range. Her voice, with a slightly nasal cast, didn’t quite have the ease or beauty it showed in “Puritani,” and there was a sense of evident calculation, probably necessary to get through a piece that was arguably still a size or two large for her. But she did step up in the passage in “Beim Schlafengehen” (“Going to Sleep”), the third song, when the soprano echoes a melting violin solo in one of the loveliest of all the lovely melodies Strauss wrote; the solo of the concertmaster, Nurit Bar-Josef, sounded a little subdued, and Peretyatko got to play the emotional trump.

Runnicles’s performance wasn’t necessarily flashy or audience-grabbing, at least until the “Enigma” Variations, but it was satisfying. Whether the conductor, with all his other commitments, is in the market for an American orchestra of his own is not clear. But his NSO debut certainly got a year of speculation, in which every conductor will come under some extra scrutiny, off to a positive start.

The program will be repeated tonight and Saturday at 8 p.m.