cambridge audio cxn(v2) with naim xs2 ??

There is no problem using a non-Naim streamer with a Naim amp. I haven’t heard the CXN, but even a very cheap Yamaha streamer worked fine when I tried it. For £250, it sounded quite good. 

Pamzz

I've only used the older cxn with naim xs2 and found fantastic value for money and sound quality

The app is reasonably stable too!!

Definitely one to audition and make your mind up on...

It should sound just fine. The only problem with the Cambridge Audio brand is that as far as I am aware it is exclusively available from the brand's owner, that is Richer Sounds. This makes it more or less impossible to audition alongside other brands. Richer Sounds does not stock much in the way of decent audio brands and so any audition on their premises is unlikely to be representative of what you have at home. 

I initially entered the 'streaming' market quite a number of years ago. At the time I expected streaming for me would be very much an occasional convenient background listen, and so my intention was to audition players from the likes of Cambridge Audio, Marantz & Pioneer. I discounted Cambridge Audio specifically because its streamer was impossible to compare directly with anything else. To my surprise I ended up switching from CD players to streamers on each of my 3 systems, and ended up (at the time) with streamers from both Naim Audio and Marantz, although I have moved on a little since then.

I would expect the Cambridge to be decent sounding and not all that far removed from the sound quality of say a 1st gen ND5 XS. However, one thing to bear in mind is that the control interface (or app) is extremely important in respect of the day to day streaming experience. So, if you decide to go for the Cambridge, do make sure that you get a demo of the app (and the way you intend to use it). I suspect that there may be a bigger difference between the merits of the respective Cambridge or Naim control apps than there is between that of the sound quality of the streamers themselves.

I personally would certainly consider a second hand ND5 XS if you can get one for reasonable money, although that would cost quite a bit more than the £700 for the CXN. Perhaps one out of the box suggestion at roughly the price of the CXN if that is your price limit wold be a second hand Linn Sneaky. I remember being quite impressed when I heard one demonstrated a few years ago.