Whether a recitalist, concerto soloist, or member of the Johannes Quartet, violinist Soovin Kim has been one of Philadelphia's more consistent and welcome classical music guests for at least 15 years.

But in his recital Wednesday with pianist Natalie Zhu, familiarity hardly meant you knew what he'd do next. The unforced gentility of his playing, prompting comparisons with Arthur Grumiaux in years past, was apparent in the Philadelphia Chamber Music Society recital at the American Philosophical Society - though not in Ravel's usually charming, suave Violin Sonata. That was reimagined as a semi-modernist companion to Webern.

Emphasizing angularity over harmonic richness wasn't a great stretch in the rhythmically aggressive first movement. But Kim's aggression intensified in the sonata's amiable "Blues" movement. The music's usual woozy comedy was serious, less like a good-natured drunk than someone coping with delirium tremens.

Elsewhere in the sonata, ornate details that would normally consolidate a larger musical idea were almost prickly. I wasn't wholly convinced by his approach and hope Kim won't make a habit of playing the piece this way. But his bracing reading was well worth trying.

After Ravel's hectic density, Webern's spare Four Pieces Op. 7 felt like rarefied breathing space. It's a cliche to compare Webern's terse, fragmented melodies and oblique, distilled piano writing to haiku. But it fits, though Kim and Zhu did give the music extroverted emotionality, allowing Brahms' Violin Sonata No. 1 Op. 78 to follow logically.

Some of the Brahms' unguarded moments got a concerto-like majesty from Kim. An often-ideal chamber musician, Zhu seemed most at home in Brahms, her radiant tone illuminating harmonic pockets of exaltation and tragedy.

A similar approach to Janacek's Violin Sonata, however, was less successful: Zhu aimed for continuity despite the composer's interruptive aesthetic, in which folksy tunes and fledgling arias are invaded by digressions and epithets. Some focus was lost. Sometimes Janacek just doesn't clean up well.

Contact music critic David Patrick Stearns at dstearns@phillynews.com.