Welle.IO Stream over Snapcast

[Hoerli1337]

Hello Community,
I am currently trying to receive several DAB+ radio stations via the Welle.IO project and output them via Snapcast.
-> DAB+ only works for me with an outdoor antenna.
Unfortunately, I have problems integrating the stream directly into Snapcast.
I have already found issues with this: 583 + 570
When I try to retrieve the stream with MPV, it does not work.
raspberrypi4b snapserver[583599]: Error while reading from control socket: End of file
raspberrypi4b mpv[583601]: pw.conf: can't load config client.conf: No such file or directory
raspberrypi4b mpv[583601]: pw.conf: can't load default config client.conf: No such file or directory

The stream can be accessed via the following URL: http://192.168.178.61:7777/mp3/0xd30b

• Sampling rate: 48000Hz
• Bits per sample: 32
• Bitrate: 72kbps according to the tool, VLC always says something between 110-256kbps

I have put together the following command:
stream = process:///usr/bin/mpv?name=DAB-Radio7&sampleformat=48000:16:2&params=http://192.168.178.61:7777/mp3/0xd30b --no-terminal --audio-display=no --audio-channels=stereo --audio-samplerate=48000 --audio-format=s16 --ao-pcm-file=/dev/stdout

When I start the stream via Mopidy, everything works.
However, I would like to make several channels available at the same time via different Snapcast streams.

What am I doing wrong?
If I open the stream normally via VLC player, I can listen to music as normal.
I have a Raspberry Pi 4B with RaspbianOS (64bit) and snapserver v0.28.0 (rev 000ea4f) installed.