The Chamber Orchestra of Europe confounds expectations with its big sound--it comes across as a full-size orchestra whose performances are impeccably detailed. Formed in 1981, the group is known for intense interpretations of the German repertoire, as is pianist-conductor Andras Schiff. For all his obvious preparation, he never plays as if he's merely re-creating what he's practiced, and unlike many musicians today he makes no concessions to the early-music movement. He's a staunch defender of performing Bach on the modern grand piano, writing of his distaste for the sound of a harpsichord in the liner notes to his latest Goldberg Variations recording: "Hands on heart, can you listen to the harpsichord that long?" He'll conduct Bach's First Keyboard Concerto, BWV 1052, and Mendelssohn's Piano Concerto no. 2 from the keyboard and stand up to conduct Bach's Orchestral Suite no. 1 and movements from Mendelssohn's Midsummer Night's Dream. The rarely heard Mendelssohn concerto is filled with rapid scales and arpeggios; its formal inventiveness is surprising given the haste in which it was written. Bach wrote the concerto and suite to be performed at a Leipzig coffeehouse--which makes them perfect vehicles for the not excessively reverent Schiff and COE. Friday, April 30, 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan; 312-294-3000 or 800-223-7114.