I have the casio 6200, and the first 12 sections of the arpeggio feature are for auto accompanying a tone,I quite liked the sound of tones that were played as a duet, but found that you had to have a preset playing alongside for this to work, this is what the instruction book said, but there is a way round this,first you go to the rhythm editor, pick any rhythm, and switch all the sections to "off",thats right every bit off,now save this in the user section, now when you just want to play a dueted tone with no backing, you select this silent rhythm you have created.