if the Arduino does WiFi and SMB file sharing you can use it as a Sonos music library.

The USB to Ethernet would work in place of WiFi.

Thanks for the quick reply Stanley

So if I connect into any of my spearkers or soundbar ethernet socket it would work just like plugging in a record deck to  an amplifier ? 

I have a sd card with my playlists 

So using  the Sonos app and Spotify if the Arduino has no wifi  what is needed ? the concept sounds good  to just create a library without downloading and making mp3s

But someone else built the adapter and it sounds very complicated to do..

as my programming  skills are 0

Thanks for the quick reply Stanley

So if I connect into any of my spearkers or soundbar ethernet socket it would work just like plugging in a record deck to  an amplifier ? 

I have a sd card with my playlists 

So using  the Sonos app and Spotify if the Arduino has no wifi  what is needed ? the concept sounds good  to just create a library without downloading and making mp3s

But someone else built the adapter and it sounds very complicated to do..

as my programming  skills are 0

Ethernet does not work like that, it connects to your router to pass data to other connected devices.

Sounds like you need help with the Araundo first to get it connected to your network. Once that is done we can help you with the Sonos part.

My understanding If its not wifi A module could be added 

Apparently no Arundo experts here, sorry.

Once you get it on your network and running SMB / Samba check back for Sonos help.