Ok, silly question time 
So if I have a USB DAC I can run volumio directly from my laptop or phone, that’s understood.
Now if I get an I2S DAC and a raspberry pi, does that mean I have to transfer all my music to another drive to connect it to the pi or do I plug my laptop into the pi or the final part to my question, or does transfer via my modem/WiFi?
I have a second question can I hook up either an xmos or anamero board to an I2S DAC and use that as an USB DAC? 
You can run the x86 version of Volumio from your laptop (with provisos … please see the x86 thread volumio-x86-debian-buster-debugging-party-beta-t13957.html).
It does not run on your phone, other than in a browser to access another device (RPi, x86, single board computers (SBC)).
Your music, however it is stored, needs to be available to the device running Volumio … that could be a samba share from your laptop, a NAS, a USB drive, USB flash drive etc.
If the music is shared via Samba or NFS over your LAN, then you should be able to access it with your Volumio device.
I have a second question can I hook up either an xmos or anamero board to an I2S DAC and use that as an USB DAC? 
[/quote]