Rachel Barton Pine, Chicago's gift to the violin world, hasn't forgotten her loyal local following. On Friday, three days after her New York recital debut, the violinist and her pianist, Matthew Hagle, appeared as guest artists with the Avalon String Quartet to provide a classy launch for the ensemble's Chicago concert series in Gottlieb Hall at the Merit School of Music. Barton Pine proved equal to the virtuoso requirements of Ernest Chausson's Concerto for Violin, Piano and String Quartet, and so did her colleagues. The violinist's poised surges of rhapsodic lyricism, supported by the piano's ripe chords and rippling arpeggios, blended smoothly with the teasing harmonies and lush colors provided by the string quartet. Artist-faculty quartet-in-residence at Northern Illinois University since 2007, the Avalon Quartet -- Blaise Magniere and Marie Wang, violin; Anthony Devroye, viola; and Cheng Hou-Lee, cello -- is an enormous boon to the thriving local chamber music scene. This is quite simply one of the most polished and dynamic young string quartets I have come across. The players pressed into the phrases of Beethoven's Quartet in B flat major (Opus 18, No. 6) with a full-throttle urgency that didn't preclude precise intonation or acuteness of rhythm.