I did not notice that the Pure2 had a separate volume level for DVB-C / DVB-S, I just turned on the channels on which the dreambox os is silent and I have sound there.
When I record such a silent channel on my dreambox os, the recording plays with the voice, but I don't know why I don't have a voice when I watch something in real time. This problem affects about 8 channels on my cable network.
I also tried to install Pure2 on the octagon, there is no sound or picture on these channels. So the hardware dreambox is the best for my cable. If only I managed to force the original system to work with sound, then DM One would be the best receiver on Linux for me