Guarneris, Graffman, and Frank

Classical musicians have no standard retirement age, partly because artistry isn't an occupation but a way of life, and ways of expressing it are constantly modified according to the physical changes of maturity. In theory.

The collective age of the six musicians onstage at the Philadelphia Chamber Music Society's season-opening concert Sunday inched toward half a millennium. Often you heard it; often you didn't. Always, the long-cultivated goodwill inspired by these performers overrode the former and certainly celebrated the latter.

Ostensibly a fund-raiser (tickets were jacked up to $50 - which similar organizations charge routinely), the concert was an unofficial reunion of the Guarneri Quartet, which disbanded in 2009 after 45 years, with Mozart's String Quintet in C minor (K. 406) and Brahms' String Quintet (Op. 111). Gary Graffman played solo piano works for the left hand. The quartet was joined by the youngster of the bunch, Pamela Frank, 44, who has long been sidelined by an injury (and much missed), but made a robust return, unfortunately in the unobtrusive second-violin slot.

Graffman had a good first half with two short works from Scriabin's Op. 9, the Prelude in C sharp and Nocturne in D flat major, both charming, fairly conservative early works, played with a no-wasted-note sense of comprehension. On the second half, the Brahms transcription of Bach's great Chaconne from the solo violin Partita in D minor had conceptual strengths one hears only from a seasoned musician. Rather than leaping in with opening chords sounding dire and majestic, Graffman built the piece over the long term to great climactic effect, though he dropped lots of notes along the way.

The unofficially reconstituted Guarneris had a lackluster first half (Mozart) but a second half (Brahms) that recalled the group's best years. Cellist Peter Wiley seized his solo in Brahms' opening movement in ways that told you to fasten your seatbelt. The trademark warmth of the group's timbre was in evidence. Some movements had beautifully attenuated conclusions, as if the musicians didn't want to let them go.

Frank looked marvelous and played with unfettered vigor. Though the second-violin writing in any given piece is usually about maintaining a solid backdrop, her few seconds of incidental solo revealed a rich tone and strong ideas about what the tone is meant to say.

Few violinists leave such a lasting gap in one's concert life as Frank, partly because live, pre-injury recordings keep arriving from various radio archives (Bruch's Violin Concerto No. 1 on the Hanssler label) and partly because Frank's appeal was such that her world-class technique was only the starting point of a generous musical personality, always brimming with ideas that were projected with great conviction. In a world of "me-too" interpretations, her performances were deeply singular. How long must we wait for more?