If the idea behind Node 2i was to eliminate laptop from your system, then Node 2i makes perfect sense. I would connect Node 2i using its RCA out to your Integrated. Secondly, I would transfer all the music from your laptop to NAS and connect the NAS directly into Node2 USB input. The default password for external NAS access is ‘admin’.
Connecting an external hard drive via the Node's USB input is the quick and dirty way but Bluesound doesn't recommend it for the long term (there are technical reasons why). That said, it's very convenient when a friend drops by with a thumb drive full of music for you to listen to and it doesn't affect your library of music which you have painstakingly created.
The easiest and more stable way is, as already mentioned, to connect an external hard drive(s) full of music to your router/switch via USB and go through the discovery/share process with the BluOS app.
Sorry, the node 2i internal DAC cannot be used with external devices.
Except for that mini-Toslink input :-)