Now I have then found the evening of the first day that the radio creaks and rustles in WLAN mode. When the music quietly makes going to sleep you can hear the noise clearly. Funnily enough, it is when the radio to "Silent" also silent, but the crack is not quiet when you do down the radio (on volume level 1 so you hear only noise almost).
I initially thought that is at the front desk and have it now times tried next to the wireless router, where I had a top signal. The result was the same. Creaking and noise ..
So I have time to connect a RJ45 cable and tried it via cable. Lo and behold, no noise and creaking!
But that is not the purpose of this radio, so I'll send it back home.
I am annoyed endlessly about it and wonder if I have a Monday device, or whether these errors at every performance. If one operates the radio always on volume 5 does not fall a noise on anyway. The radio itself was actually a super cool device and I'll return it very reluctantly, because I do not think to find a similar cool device for so little money ..
Edit:
What I have found out: If I operate the radio via WiFi, but external speakers connect I have no creaking and noise. Ergo seems (no matter whether good or bad) to influence the boxes of WiFi reception. Poorly shielded possibly being the keyword.
Conclusion:
Either external speakers or operate with network cable. Ergo, the radio has missed the whole purpose and gets instead of 5 only one star. Without this fucking noise it would become 5.