Is this possible and did someone already tried? I havn't found anything in the Forum.
I found a Software called Raumserver to be installed on one of the speakers.
https://github.com/ChriD/Raumserver/wiki
Then it can be controlled with HTTP-Commands like
How can I integrate this in Z-Way to trigger commands from a Z-Wave-Switch?Control Requests
Control request can be sync or async(default) and are made on following url
http://[ip]:[port]/raumserver/controller/[requestCommand]
play
With this request you can start or resume playing the current playlist for a zone or for all zones
/raumserver/controller/play
/raumserver/controller/play?id=Wohnzimmer
stop
With this request you can stop playing the current playlist for a zone or for all zones
/raumserver/controller/stop
/raumserver/controller/stop?id=Wohnzimmer