Hi@all!
I thought I would like to report my recent experiences…
In April 2018, I gave my HDX in payment (foolishly, I know) and received a brandnew Unity Core because the dealer told me that the new Unity Core sounds better through the nDAC than the HDX. I stupidly believed it. Duh me. 
So, I had the Unity Core with a 2TB SSD for several months and in the beginning I was very happy. But more and more I realized that something is not to my acquired taste…the sound became a bit too “harsh” for my ears and I kind of missed the warmth of the HDX…
In October another dealer offered a demo ND5XS and I exchanged my Unity Core (and some Euros) with the ND5XS.
And straight out of the box, the ND5XS brought the smile back into my face. What a wonderful sound through the nDAC…all harshness and the accentuation of the higher end were gone…
In my humble opinion, the Unity Core sounds great, but it can´t touch the feet of the ND5XS and certainly not those of the HDX.
The ND5XS sounds so much better than Unity Core and I am happy again, running a Synology NAS with ASSET into the ND5XS.
As an addition:
In October 2018, my Supernait 2´s right channel emitted strange noises and it was sent to NAIM in Salisbury where it was checked and the right channel of the preamp was repaired.
It took 3 months and in the meantime my dealer gave me the new Nait XS2.
I was very impressed with the XS2. It sounded wonderful and I thought it is great value for money.
I even read in the old forum that some preferred the XS2 over the SN2 and I wondered about that…
But as soon as I received the repaired SN2, all “doubts” were smashed to pieces. The SN2 is in a different league altogether and sounds now absolutely stunning again.
Thank you NAIM for the nice repair.