“So the Bridge isn’t required for Roon, but you’re recommending it…what advantages the Bridge would have rather than feeding the Roon signal from my Nad streamer to the DSD?”
@stuarthartenhotmail-com: I can’t speak to any advantages compared to your NAD streamer as I am not familiar with it. Roon and the DS Sr./Bridge II combination play well together and sound excellent. Using Roon 1.6 with Tidal and/or Qobuz integrated into the library it manages really makes this a “we are living in the best of times” moment in terms of access to music. I recommend the Bridge because: a) it sounds and works great with Roon (and JRiver Media Center, my preferred “critical listening” music software for playing ripped and purchased files stored in my iMac); b) it makes the DS Sr. a MQA player (full-on “origami” on tap); and c) the combination does not require a super-complicated signal path (or separate renderer/digital player) to get a high-quality digital signal to the DAC. Others prefer to take the specialized renderer/player path and report superior performance that I am sure can be obtained.
Like I said, I am not familiar with your NAD but if it does everything you need, you may be very satisfied feeding Sr. directly (via USB?). Keep in mind that conventional wisdom tends to judge USB as a potentially (but not universally) inferior digital pathway to a DAC. This is a general issue, and the subject of great debate; not universally true depending on the specifics of one’s set up.
If I were you, I would grab a Bridge Ethernet card on trial and try out your system with a variety of configurations using the kit you have on hand and pick what works best for you. There is 0 risk in giving the Bridge a spin.
Maybe some others will chime in.
Have fun/hope this helps a little.