Christoph Eschenbach, Ravinia Festival’s new music chief and a prime candidate to succeed Daniel Barenboim at the helm of the Chicago Symphony Orchestra, knows how to mount blockbusters. In residence at the CSO for the next two weeks, he’s slated a couple of heavyweight programs that bring forth the late romantic era’s preoccupation with size. Mahler’s Symphony no. 8, to be performed in week two with an impressive vocal octet of mostly up-and-coming soloists, is deservedly nicknamed “Symphony of a Thousand,” even though the forces assembled at the Medinah Temple, the CSO’s temporary home during Orchestra Hall’s renovation, will number a mere 400 plus. Eschenbach, a thoughtful taskmaster, should coax sonic splendors from the augmented orchestra and choruses and fulfill Mahler’s intention of matching the noble spirit of Beethoven’s Ninth. Admittedly the maestro’s week one all-Tchaikovsky affair is fairly pedestrian, with three pieces all too familiar to the orchestra and popular with concertgoers. After all, what novel spin can a pianist bring to the romantic dementia of the First Concerto? In this case, however, the spin is on the soloist: Tzimon Barto. A 270-pound bodybuilder with Brad Pitt looks–definitely an unusual distinction for musicians–Barto hails from an Orlando suburb and studied at the Juilliard. In the late 80s he hooked up with Eschenbach, who’s become a mentor. Barto’s physical strength allows for extremes in dynamics and the widest variety of tonal color–not surprisingly his forte right now lies with the flashy Tchaikovsky and Rachmaninoff showcases. It’s safe to predict that his Tchaikovsky First will be speedy and loud–no wallowing in petty and pretty sentiments. Also on the bombast-heavy program are the 1812 Overture and the Fourth Symphony. Thursday through next Saturday, May 25, 8 PM, and next Sunday, May 26, 3 PM, Medinah Temple, 600 N. Wabash; 294-3000. TED SHEN