You could use LUUP code in scenes to send the http commands in the API example to your speakers.
Example (based on you API link)
luup.inet.wget("http://192.168.1.38:11000/Play?id=0", 5, "", "")
This will play 1st song from playlist. The "5" is a 5 second delay to allow the http request to be processed by the target.
You can add a variable to parse the result of the http call and determine if it was succesful or not.
mysuccess = luup.inet.wget("http://192.168.1.38:11000/Play?id=0", 5, "", "")
mysuccess will hold the return value. As I'm not familiar with bluesound I'm not sure what values it returns and what they indicate.