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A couple of times each season the Chicago Symphony Orchestra slims down to an ensemble of chamber music proportions and addresses repertory not usually presented on subscription concerts at Orchestra Hall.

The programs often focus on Baroque music played in an historically aware manner, but for some time now pianist-conductor Mitsuko Uchida has extended the exploration to Wolfgang Mozart and other composers of the Classical and early-Romantic periods.

Thursday night’s attractive program offered two Mozart piano concertos — Nos. 6 and 26 —surrounding Robert Schumann’s song cycle “Frauenliebe und -leben” (“Woman’s Life and Love”). Uchida played the former while conducting first 25 and then 41 CSO members from the keyboard; in the latter she alone provided piano accompaniment for soprano Dorothea Roeschmann.

Next week Uchida will take the concertos to the Cleveland Orchestra where the Schumann will be replaced by Mozart’s Symphony No. 34. The vocal music will be on Roeschmann and Uchida’s April 22 recital of songs by Schumann and Alban Berg at Carnegie Hall.

The successful CSO program approached what conductor Erich Leinsdorf used to call “mixed media ‘academies,'” which combined readings, songs, chamber music and orchestral performances in a much-needed change from the overworked concert hall pattern of overture, concerto and symphony. Thursday’s effort might have gone further. Nonetheless, it was a refreshing way to broaden subscription concert repertory while still honoring the CSO’s conservatism.

The Schumann actually proved a bit of a risk, given that Adelbert von Chamisso’s texts for the eight songs present a woman’s life wholly in terms of love for a man. Such sentiments do not go down easily these days, and contemporary singers approach the songs’ wide-eyed, over-awed ecstasy from the outside rather than from beliefs firmly held within.

Roeschmann was musically satisfying (despite several unmarked crescendos and a fussy rolling of Rs) but wanting the last dollop of expressive conviction. Her voice is lighter in weight and color than that of contraltos who sang the work in bygone days. Yet she limned the arc from first meeting to the death of her husband purely and securely even if the account was less inward than Uchida’s hyper-sensitive accompaniment. In any event, it warranted an encore, Franz Schubert’s “Lied der Mignon,” Op. 62, No. 4.

Uchida’s Mozart is by now well-known. It owes nothing to the angularity, clarity and briskness of historically informed performance. It’s extremely congenial and given to soft blending and subtle color. Almost no one gets as much tenderness from slow movements.

The approach worked beautifully with the Concerto No. 6, K. 238, raising its stature and making the central andante ravishing. It had the benefit of Mozart’s own cadenzas. The longer, fuller and more robust Concerto No. 26, K. 537 (nicknamed “Coronation”), was likewise pliable and lyrical, but more predictably so. Here Uchida used a cadenza by Wanda Landowska, reminding us that the harpsichordist was also a most affectionate servant of Mozart.

The program will be repeated at 1:30 p.m. Friday and 8 p.m. Saturday at Orchestra Hall, 220 S. Michigan Ave.; $43-$139; 312-294-3000; cso.org.