The Orion Ensemble concludes its 29th season with a concert program welcoming guest violinist Stephen Boe and guest violist Roger Chase and featuring works by Mozart and Borodin at three venues: New England Congregational Church in Aurora (May 8), PianoForte Studios in Chicago (May 11) and Nichols Concert Hall in Evanston (May 15). The Chicago and Evanston performances also will be available via livestream.