Hi Gino! Thanks for the reply! I have already written Thomann now, though, as the issue seems to match exactly with both your and kongsfingers descriptions above, where the solution seems to be a replacement. It sounds just like in the soundfiles found here in the thread, and just like kongsfinger describes, it also went away after a bit of playing time, but comes back again after having turned the unit off, so somethings clearly wrong. I keep my fingers crossed that the replacement will go smoothly, because apart from this, it seems a really interesting and great sounding synth.
(Have added a short audio example for others who might have the same issue. Just the init patch with filter closed a bit. No fx, resonance or anything.)