The group's early sound was geared more towards psychedelic rock with only occasional classical influences. Following O'List's departure, Emerson's control over the band's direction became greater, resulting in more complex music. The absence of a guitar in the band and Emerson's redefining of the role of keyboard instruments in rock set the Nice apart from many of its contemporaries. He used a combination of Marshall Amplification and Leslie speakers in order to project a full sound to compensate for the lack of a guitarist.