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Orli Shaham (in white wig) and Nicholas McGegan

Pianist Orli Shaham (in white wig) and Nicholas McGegan, backstage at Powell Symphony Hall. (Photo by Adam Crane)

There are many reasons to seek out live performances: the excitement of hearing music as it’s being made, without editing or retakes; acoustics that can’t be matched at home; the sense of community that comes from a joint experience.

Conductor Nicholas McGegan adds an extra dimension to any performance in the palpable joy he brings to his music-making, from the moment he bounces to the podium until the final bows. McGegan, renowned as a Baroque and Classical specialist, turns the members of the St. Louis Symphony Orchestra into a fine facsimile of a period band, dishing up stylistically impeccable and utterly committed music-making.

On Friday morning at Powell Symphony Hall, the SLSO offered music by three Germanic masters of the Classical period: Christoph Willibald Gluck (1714-1787), Wolfgang Amadeus Mozart (1756-1791) and Franz Joseph Haydn (1732-1809).

Gluck led off, with the Ballet Suite from “Don Juan.” It’s a set of brief dance segments in many styles and moods, from the lighthearted to the furious, with an impressively stormy end, nicely explored by McGegan and the small orchestra.

McGegan’s style is well-suited to the music of Mozart; so is that of pianist Orli Shaham, and there was a happy interplay of soloist, conductor and orchestra throughout Mozart’s Piano Concerto No. 9 in E-flat major. Mozart’s music plays to Shaham’s strengths — a light touch, a sense of humor, the ability to express a sunny outlook even through storm clouds — and she gave a strong performance. The near-capacity house rewarded her with an ovation; Shaham thanked them with an encore, the first Menuet from Bach’s Partita No. 1 in B-flat major.

After the intermission, McGegan led the Entr’actes from Mozart’s opera “Thamos, King of Egypt.” It’s minor Mozart, but even minor Mozart is worth hearing, and it was well-played.

The final work was Haydn’s Symphony No. 98 in B-flat minor, one of his inventive “London” symphonies, with a hymn-like tune in the second movement and superb writing throughout. There was a surprise at the end: In the violin-piano duet that ends the final movement, with Haydn at the keyboard for the première, associate concertmaster Heidi Harris was joined by a surprise guest: Shaham, in white wig and knee britches (reportedly her idea), for the perfect conclusion.

At the beginning of the concert’s second half, McGegan stepped out to acknowledge longtime associate principal oboe Barbara Orland, who retires with this weekend’s concerts after almost four decades in the SLSO. She’s a gracious individual and fine musician, and McGegan offered a recollection of his own: “I remember a wonderful performance of the Bach Wedding Cantata” with Orland “playing it as beautifully as I have ever heard anyone play anything.” Orland had two notable solos in the program, in the Gluck and the second Mozart, and played them both with distinction.

Nicholas McGegan, Orli Shaham and the St. Louis Symphony Orchestra

When • 8 p.m. Saturday

Where • Powell Symphony Hall, 718 North Grand Boulevard

How much • $29-$109

More info • 314-534-1700; stlsymphony.org

Sarah Bryan Miller is the classical music critic for the St. Louis Post-Dispatch; she has also written on a variety of other topics.