It was an old-fashioned program, ending with the acrobatics of the Saint-Saens “Introduction and Rondo Capriccioso,” that brought the Phillips Collection audience to its feet in appreciation on Sunday, and that’s not an audience usually given to such a display of enthusiasm.

Violinist Misha Keylin and pianist Robert Koenig were a well-matched pair as they wended their way through the wistful Mozart E minor Sonata, K. 304, the Brahms D Minor Sonata Opus 108 no. 3, George Rothberg’s neo-romantic “Rhapsody and Prayer” and a couple of pieces — the Tchaikovsky “Melodie” and the Saint-Saens — that have often been cast as encores, but weren’t here. They grew more comfortable and idiomatic as they headed toward the Rothberg and beyond, and by the time they hit the Tchaikovsky (and Keylin freed himself from the music and music stand) they were absolutely in the zone. The Tchaikovsky soared and the Saint-Saens, powered by Keylin’s splendid bow-arm, was smashing.

The Mozart didn’t fare quite as well. Keylin has adopted a sort of all-purpose vibrato, quick and wide, that is fine for the ecstasy of the Tchaikovsky but that, lavished on the Mozart, just sounded nervous. In Koenig’s hands, loud passages had uncomfortably non-Mozartian sharp edges. The Brahms, which was nicely broad, bold and unfussy, had moments when the violin’s intended anticipatory attacks couldn’t quite mesh with the piano’s down-beats. For his part, Koenig did a particularly admirable job of shaping the phrases of the Brahms last movement.

Rothberg’s short, neo-romantic piece fit in well with the rest of the program. Keylin’s performance was happily free of posturing (but interrupted briefly by a struggle to seat his mute securely). He managed its technical challenges with aplomb and accuracy and offered it up as a coherent and attractive extension of what Brahms might have considered had he lived another 100 years.

Reinthaler is a freelance writer.