just got a new Callisto in the mail the other day and have a noticed a couple issues with it: 1) when turning any? of the knobs up past noon, i start to hear a low pitched 'thumping' noise. the speed of the thumping gets faster as you tweek the knobs higher. 2) a few times while playing thru it, I turned the Mix knob up to 100% and the effected sound went away! I rolled the knob back to 0% and up again and the effected sound came back. Is this normal for this pedal? any other Callisto owners have this problem?