On Saturday, von Oeyen touched the soul of the collective audience with Mozart’s Piano Concerto No. 20 in D minor, K. 466…he showed off his brilliant technical accomplishments in a variety of moods, from the simple, plaintive opening theme to the turbulent finale. The stunning chromatic passages flowed like a purling stream, and the soloist played the lovely melodic Romanze movement, so familiar to many serious piano students, with affectionate elegance.