Incidentally, the flicker has not occurred since I started using a different power supply.
Just for your information.
You should really think about whether you shouldn’t include a different power supply. That seems to cause a lot of problems.
The overall noise has now also decreased to a tolerable level that I can work with. In between I was a little desperate because I really like the MDX, but the noise bothered me a lot.
I’m pretty happy now.
For those who are interested: I now have a “LEICKE power supply 60W 12V 5A”.