The word maverick suggests something quirky and light, but Michael Tilson Thomas finds profundity in these Americans, and brings a reverent care and finesse to their music. The San Francisco Symphony plays with extraordinary delicacy, which makes the tumultuous movements such as the ending of Varese's Ameriques all the more overwhelming. Jeremy Denk's performance of Cowell's Piano Concerto is incisive and delicate, but the revelation of this CD is Lou Harrison's little-known and enchantingly mysterious Concerto for Organ with Percussion Orchestra.