If you raise the INPUT L / R level on the MASTER page with the state that a somewhat complicated sequence is played (using more than 2 - 3 tracks and more than 5-6 voices), the probability of 2/1 Petit noise will be pronounced at the beginning of the measure (even if the sound source is not connected).
Does this symptom also occur with Digitone that you have?
I recorded symptoms in a video:
https://www.instagram.com/p/BeuoWa1l36g/