The causes? Tried everything possible for many hours. Without Success.
Strange, because these problems did not exist when components are connected to the optical digital input of the receiver.
At first I wanted to contact the customer service at Harman Kardon. But that's not easy.
Therefore, as Last attempt changing cables.
Lo and behold, the noise has been reduced by at least. 50% after connection to the Sunshine cable.
The sound: Simply outstanding.
The parallel cable bought a German well-known manufacturer, 3 x more expensive, did not improve.
Therefore 5 stars.