Sound via snapclient is horrible

I’m testing volumio (3.616) and activated at commandline the internal snapserver and set snapfifo in mpd.conf to enabled. Everything works fine, but the sound is horrible when I connect from other snapclients to voluminos snapserver.
The snapclient is ok, it works fine with another spapserver.
I tested volumio on a raspberry and also on x86 … same result.
What is making the sound streamed by volumio snapserver so horrible?