Basic system configuration questions

I have just come across Volumio and it would seem to be just what I need.

I am familiar with Linux and already use a Raspberry Pi as my local DNS etc.

My questions are more to do with how to configure the audio side of things. We have several sound systems around the house, internet radios, etc. My main HiFi system is an Onkyo TX-NR616.

So, having installed Volumio on a Raspberry Pi connected to my LAN how do I get it to send audio anywhere? Do I actually need to connect it directly to the Onkyo TX-NR616 or can it use the network? Can Volumio talk to my internet radios and use them as players?

Is this documented anywhere? I couldn’t find anything about this on the Volumio website.