I just bought a anti pop sound circuit board with delay timer to try if it can help.
It is so loud, that i am afraid that the subwoofer could break.
It also comes from the speakers but it not so loud.
Therefore i will try that device until it is found what causes some head units to pop.
In normal use everything is fine, but after some days the head unit turns off,and then you can't do anything about it. In normal use you can choose how to reboot but not when the head unit is completely off.