I like the Aurender idea a lot, they make streamers that are not too costly...but what you get is phenomenal in terms of SQ, USB 2.0 audio output, user interface (conductor app) and internal storage (most have at least 2TB's) plus external drive connection via USB. Regardless of which model you choose, its well worth the price in every way! Also, I would look for a Digital interface processor that would except USB audio IN and then have SPDIF as a Output. Monarchy Audio may make something like this , I would call them. Otherwise get the Aurender streamer and buy a different DAC that will take USB audio 2.0. IMO.
Matt
Matt