If it works well enough with Serviio then I'd lean towards a NAS that can run that. The Superuniti has an LCD display so you can browse a UPnP/DLNA server, I'd try with a PC running Serviio to get an idea of how it works before pulling the trigger on any NAS just yet. The UPnP Mediatomb server can also be gotten going though it is quite complicated to setup. It is possible to replace the DLNA server on QNAP/Synology units with Serviio which also has a PC version you can try. * Netgear also use Twonky, though they have another called miniDLNA. * Synology use their own in house DLNA server, from what I heard it is not great for large music collections though again that largely depends on your needs.

* QNAP use Twonky the licensed DLNA server, you can try out the PC version. How well it works may depend upon your needs. If your using DLNA then be aware that its a minefiled as the standard is so fragmented. I expect all of them will suit your application, but do check about the capabilities of their DLNA servers. Expect to pay between £150 - £200 for a mid-range 2-bay NAS without disks, and another £180-£200 for a pair of 2TB drives to go in them. The major players in the domestic/home office NAS market are Netgear, Synology and QNAP - they all do 2-bay units that will suit your application. BTW, running a NAS in a data redundancy mode is not an alternative to having a backup - so you should budget for another 2TB external drive (USB/eSata) to use as a backup device. If you're going to store HD video as well as 1000 CDs in Flac format then a 2 x 2TB unit is the least you should be looking at.

As has been mentioned, DLNA is a more standardized sub-set of uPnP, you'll want a NAS with a DLNA service that supports the audio files that you want to stream to the Naim unit, which will presumably be Flac ? Be aware that not all DLNA/uPnP servers support Flac (or other non-MP3 audio formats), so it's something that you need to check for.

Best nas for home music streaming