OP
THe Node 2 is a renderer. The files on the external HD can be read by the Node 2 and then either convererted in analogue in it's own DAC or sent digitally to an exernal dac.
Whatthe Node 2 can't do is serve as a DAc for another digital component, such as the Apple TV, or a CD player, or even a regular TV that you wish to run through your AV system. You can use your current DAC for all of these components but if you sell off the Schiit and rely on the internal DAC of the Node2 to try and play these other pieces through your system you will not be able to