NAS Storage and Streaming for Hi Def audio, What NAS Hard drive system best for Mac..


I've been researching on creating a NAS / Streaming system now that I've settled on the L.K.S. Audio DA004 DAC.
I've hit a wall in regards to which would be the  best  NAS Hard dive system to start with, and with hopes that the NAS storage and streaming system I will be able to build from will last for years. I know with the ever changing Audio world, nothing seems to permanent, but need a good a place to start and go from there.  I've narrowed it  down to 3-4 system', But I am open to any suggestions from the group that could work best with my Mac products. I'm looking for a 4-5 Bay system that I'll be able to build from to increase storage as my library grows. My thoughts are to start off from 8-12 TB. I do have a music library that I  use with  itunes, Tidal, Pandora, etc. But I would like to build a library of as high of HI Def files as possible, so I probably will start from stratch and bring over what ever works. I don't have a dedicated music network Device. I bought a Cambridge 851n, But returned it because I did not like it upsampling all music and not being able to turn it off/on.  I would like to run the system by iPad either fixed in the wall, or iphone and with the main iMac computer in another other room using eithernet Cat5- 6, or higher if needed. I'm Down to :  QNAP TS-451  , Drobo 5n2, Synology DS 418 . WD MY Cloud EX NAS. Each have a lot to offer, and the more research I do , the more I confused I get. I'm at a point where my research on the internet isn't revealing anything new or more to add for Audio, So I'm reaching out to the group for some help at this point. 
Thanks again for your help.
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I appreciate all this good info. I looked into the Melco devices and they have some really good reviews and great info on high end streaming and stoarage.   But it almost feels like it’s more of a high end music server with the addition of small NAS storage . But I appreciate how they developed there HI Def storage/NAS of building the storage with more like smaller flash drives to developed for the one Storage for speed and hi end quality, ( that is not a exact technical description, but a quick overal review on my end).  How Melco is creating a dedicated high end audio music streaming and storage, vs using and going the universal market of Hard disk storage.
I did like the QNAP line for what it has to offer, but wasn’t aware of the line that you recommended. I appreciate the WD line for speed and cost savings, but wasn’t aware of the process for additional storage. Looking into the Melco has brought forward an important issue of the noise added when using universal NAS data storage vs a dedicated Melco audio line that has developed for hi end audio. Now it’s a matter of cost and dollars, what I can afford, or more important is starting off in the right direction, no mattered of  the higher cost of the dedicated audio music streamers and storage, but unfortunately their a Finacial restraints that I also have to consider. I’m still open to suggestions on the best NAS storage system to start and build from with music streaming still a large part of the complete NAS system.
While reading reviews on the Melco N1A/2 , it lead me to a the 
Innous line of music Servers which also stood out. The one I was looking into was the : Innous Zen MK3 1 TB music server for apx.
$1,850.00 which Had some nice reviews for it delievery of hi end music. But this also has got me a little more confused on the direction of my digitial storage and streaming, though it’s getting very interesting.
IME the best approach is computer-grade i5 or i7 NAS in conjunction with high-performance Ethernet-to-USB renderers like Micro- or UltraRendu or SOtM.  Separate the EN-to-USB conversion with audiophile pieces from the computer and storage.  It's scalable and relatively cheap.
After reading  more on the Melco N1A/2 music storage and streamer, which so far has received great reveiws , talks about the pick up of noise with the conventional Hard drives and cables, would what you suggest be doing that with all the various drives and cables. Honestly, you kind of lost me with some of the technical specs that you described. I’m just now researching the terms you described, But what Melco was describing inregards to the difference’s of a dedicated audio Music storage and streamer makes some sense inregards to build up of noise. 
Again , I’m very new to this technology and I’ve been reading for the last couples of weeks , and I feel I’m just at the tip of the iceberg when it comes to all this technology with high end audio storage and streaming.

I’m basically an analog guy but several years back wanted to get into digital. Went thru a LOT of DAC’s but did use a G-Technology 4TB RAID 2 NAS so it’s always backing the data up. Have never had an issue and even though I still enjoy analog running out of the NAS to a MAC (using Pure Music) it sounds wonderful.