Though choice of soloists is often an important component of Chamber Orchestra of Philadelphia's sense of alternative symphonic experiences, previously unknown guest conducting talents can feel like an even more welcoming ambush.

Sunday's headliner at the Kimmel Center's Perelman Theater ostensibly was Sean Chen, a young pianist who has placed well in competitions (the Van Cliburn, for one) and is a nominee for a 2015 Leonore Annenberg arts fellowship award at Penn. But the concert started with Haydn's little-known overture to the opera Armida, conducted by the lesser-known Nir Kabaretti with a solidity not heard consistently since Ignat Solzhenitsyn's departure and, more than that, a distinctive, glistening personality.

Though this level wasn't always maintained (you heard the spots when rehearsal time ran low), Kabaretti may be the kind of conductor the orchestra needs when music director Dirk Brossé is off conquering the film world. The 47-year-old Israeli projects unfiltered enthusiasm and commitment to what he's doing. The Haydn overture didn't warrant a spoken introduction (it's good, not great), but he couldn't resist giving it anyway, so enamored is he of the music.

Other program choices were off the beaten track: Mendelssohn's charming Sinfonia No. 10 (repertoire familiar from Solzhenitsyn's years) and Verdi's String Quartet expanded for chamber orchestra by Arturo Toscanini - a footnote but a fascinating one.

Verdi had the chops to write a string quartet, but without a theatrical scenario, his usual lyrical gifts were oddly untapped. The exposed string writing sometimes pushed Chamber Orchestra to the edge of its resources, though the performance took an impressive turn at the end when Kabaretti made the tempo accelerate like a shot. The orchestra was with him all the way and hardly broke a sweat.

Chen played Mozart's soul-exposing Piano Concerto No. 27, showing how the pianist gravitates toward late-period works (having played Beethoven's "Hammerklavier" sonata at the Cliburn). Initially, the concerto's melancholy undertones were absent - until he hit the first movement's thematic development. Something shifted, and a more complete picture of Mozart emerged. The rest of the concerto wasn't always so insightful, but was beautifully played at every turn, a reminder that one does welcome breaks from flashier, more invasive spirits such as Lang Lang. Perhaps Chen has it in him to eventually deliver the best of all worlds.