The keys in a reproducing piano are actuated by a plurality of solenoids, one for each key to be played. The solenoids are arranged along the width of the keyboard and deviated from each other in the front-back direction of the keys in a staggered manner. A consequence of this arrangement is that the mechanical lever advantage of some solenoids is greater than the mechanical lever advantage of others, and as a result, some keys are played more loudly than others. In order to correct this problem, the drive applied to a solenoid is adjusted to compensate for the mechanical lever advantage, thereby allowing a performance to be accurately reproduced.