 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 . 
