Encores come in a few standard shapes and sizes: the ardent, lyrical cantilena; the short, vapid bit of pure virtuosity; something more enigmatic or contrapuntal. Violinist Hilary Hahn wanted to expand her range of encore choices, so she commissioned a set of new encore pieces from composers around the world. Her recital on Saturday night, presented by the Washington Performing Arts Society in the Kennedy Center Concert Hall, featured the Washington premieres of some of them.

The encore has a special place, offered by the performer as a gift to the listener and sometimes mentioned but generally not reviewed by critics. It is often a way for musicians to play music they normally would not include in a serious program, as a guilty pleasure. It is not necessarily something one associates with new music that might not sit well with all listeners, and that is the challenge facing Hahn’s project.

Grammy Award-winning violinist HIlary Hahn. (Peter Miller)

Some of these pieces are too involved, too acerbic to serve as dessert. The ones that might succeed as encores embraced more conventional sounds: a Paganini-like scherzo from James Newton Howard; fizzy American fiddle dances that steered clear of Mark O’Connor territory, from Mason Bates and Mark-Anthony Turnage; a bit of Kreisler treacle from David Del Tredici.

In three more substantial pieces, on which the encores were draped, pianist Cory Smythe came close to overshadowing his partner by the ferocity and finesse of his technique. He had a light, early-music touch in a subdued Corelli sonata (Op. 5, No. 4), all broken chords and semi-improvisatory flourishes, and was the more striking performer in Faure’s saccharine, rambling first violin sonata. Only Hahn’s disciplined rendition of Bach’s D minor Chaconne, from the second solo Partita, made it clear that she was indeed the lead performer. By keeping the tempo more or less constant, Hahn allowed the piece’s kaleidoscopic patterns to emerge.