From my experience a DAC does matter w/ the Bluesound Node 2i. I had one and it was decent. Used the coax and fed that into my McIntosh C47 and there was a major upgrade in SQ. Likewise when I got a Simaudio 280d DAC, it sounded much better through the Simaudio then on it's own. But the streamer isn't the best quality. Its good, but not great and a $1000 streamer/DAC sounds better then the Bluesound through a $3000 DAC. But at least Bluesound app is polished...
