OP,
”I always assumed to use it as a transport for the digital signal from the BNS and never use it’s internal DAC. So as long as the data file is “true” shouldn’t the SQ be determined by my outboard DAC?”
That is a very logical assumption… but just not true. I have used many streamers from iPhones, MACs, through $3K, $5K an finally I own a $22K Aurender flagship steamer… each step provided better sound (you must have a DAC up to the task of course). My Aurender is simply stunning and brought my digital end to the level of performance to the high end analog side of the system.
I also have an Aurender N100 in my headphone system. You can see my systems under my UserID.
I highly recommend looking at an Aurender streamer… they come at many price levels. They only make streamers and many of the best.