Do I have to use a streamer/renderer to play music from an NAS?

Wow, what a wealth of information. I appreciate it so much.  But, honestly, I just want to listen to music that sounds great and is easily located and selected. I spent too many hours configuring networks, etc. when I had my own business. I want simple but good sounding. Much of this seems too complicated for my tastes. Is the Bluesound Vault II reliable, especially the built-in ripper?

A huge resounding YES on the Bluesound Vault 2.
Used one for two years with zero issues on streaming or cd ripping.
It is very versatile although it’s weak point, imho, is its internal dac.
For a grand its a simple powerful way to get round any tech issues, it s nearly plug and play.

@kumankahn.  But, honestly, I just want to listen to music that sounds great and is easily located and selected.

Looks like you have to main goals for your music: (1) sounds great  and (2) is easily located and selected.

(1)  Seems like a hardware choice.  Since your RC-1590 has a DAC, I'd look for a pure media server.  Take a look at the Innuos ZENmini  
http://www.innuos.com/en/catalog/go/zenmini-mk3-1tb-hdd. 

They are simple to setup and configure; are CD rippers; and come pre-loaded with Roon.  They cost more than the Bluesound Vault 2.  I use a Zenith MKII.  The SQ is outstanding.  Check out the online reviews.

For connectivity, the ZENmini has two Ethernet ports or a USB port.  In your case, you would connect your LAN cable to the ZENmini "LAN" port, and then the ZENmini "Streamer" port to you RC-1590 "Ethernet" port or the ZENmini "USB" port to you RC-1590 "USB" port.

(2) Seems like software choices.  I'd give Roon a try.  If that doesn't work, there are a lot of other choices.

"But, honestly, I just want to listen to music that sounds great and is easily located and selected."
:-)  Don't we all. Let us know when you find it.
Ok, seriously, its not that easy, but yes BlueSound is supposedly pretty good. But you still either need to co-locate it with your DAC, or you need to get something to terminate the network in another room and feed either USB or SPDIF to your DAC, and therein lies more complexity if you want good sound.  Its mostly about digital noise on the line and jitter.
G

Again, thank you. Many ways to get there. I didn’t know about the Zen Mini. I like the specs for it. It seems to match the RC-1590 better than the Vault II. The Zen Mini can handle DSD, as does the RC-1590.