OP
The Node2i is a streamer. You can stream music on a HD, including High Rez files. It plays Internet Radio. As mentioned previously, it interfaces with every streaming service imaginable.
It has coax, optical, and usb outputs to attach to a DAC. For me, coax and optical sound the same, usb a little less. Ymmv. I wouldn’t get hung up on what cable to use. It also has analog outputs that can connect to your pre amp, so you can test the quality of the DAC in the the Node2i vs the the Marantz DAC. For you as a newbie, the Bluesound products are the sweet spot in quality, price, ease of use. If you decide streaming isn’t for you, you haven’t made much of an expenditure. The quality is pretty good and you may never feel the need to upgrade. If you really get into streaming, you can buy better sounding products for greater outlay.