Best Connection Between MAC and NAD

I'm new to this and still a little confused.  Considering the spec info just mentioned regarding the MDC2 BluOS-D module which I have and is part of my NAD C 399 does that mean that I really don't need an additional streamer such as the Bluesound Node because the MDC2 BluOS-D module is already providing that function at a roughly equal high sound quality?  

And if that is the case, going back to my original question, what is the best cable connection between the MAC and NAD?  Please advise.  Thanks!

Great suggestions on the hardware.  Thanks!

I started out using Apple Music because I've been using earlier iterations of Apple Music for years.  Then, the NAD dealer rep showed up to set up my system.  He began to praise how Tidal provided much better quality audio.  So, now I've been testing out both services.  In the mean time I've been hearing about how Apple is working to improve its sound file quality.  So, now I'm not sure which of them to pursue.  Please let me know if you have any suggestions regarding a preferred service - Apple or Tidal - and if either has better features?  Thanks!

Thank you so much for your great response!

I have a follow up question.  You said that you use QoBuz.  In comparing Apple Music and Tidal, it appears that Tidal has the edge on sound quality.  I'm playing the streaming into a NAD C 399 with MDC2 BluOS-D module attached to new, good stereo speakers and subwoofer.  So, sound quality is important to me.

Your choice of QoBuz over Tidal would suggest that QoBuz sound quality is better than Tidal.  My question is overall whether you think QoBuz is better than Tidal in sound quality?  Thanks!

You've been extremely helpful!

Many Thanks.  Now I have my work cut out for me!