Why buy Bluesound Node2i vs. Marantz AVR for playing music from NAS or streaming services?

I use the node 2i to very good results into Yiggy 2.
Change out the power cable and use a good coax SPDiF cable you be rewarded.
You will not find a used Yiggy 1 or 2 for less than 1600.

What power cable and digital cable do you use 

Basic power cable. 

Audioquest Carbon Optical from Node2i to Parasound

btw for external DAC, which is a better fit for my system - Qutest, Yggy, Benchmark DAC3, Ayre Codex?  I listen to all kinds of music incl classical, jazz, rock, pop, vocal 

Because the Vault 2i is awesome.... it has completely changed the way I listen to music.  Not only is it great in my main system, I can send its content to my Blutooth speakers in bathroom and garage.  Best money ever spent on a component with respect to what you get for your money in one box.  I am actually listening to it right now...at 430 AM...

I send its digital output to a DAC but it sounds pretty good through it's analog out.  It has a combo digital optical / analog inputand a sub out.  You could literally drive a pair of powered speakers and sub.  I usethe analog input for my tuner.  My pre has no remote volume so at night I just use the Vault's volume.  

It can work with a number of music services.  It has bi directional Blutooth, it can receive content from a phone or tablet.  Want a family member to stream to your stereo without physically touching it?  Just have them putrhe Blu OS app on their device and they can stream their contentto the Vault 2i.  The Vault is worth the $$$ in my opinion.  

The Bluesound will give you a lot more options for streaming - Qobuz, Tidal, Radio Paradise, and much more.  

Connecting to an external DAC will improve sound quality, but the DAC in the Bluesound is quite good for the price.

You should notice a difference in sound quality running the Bluesound and external DAC through your Parasound gear over using the amp/DAC in your Marantz receiver.  

The Bluesound app is very good and makes it easy to use your phone to select music from either your NAS or from streaming services.