@Rjt36 May I ask:
If you like the Naim sound, stick to Naim.
If you have the budget for a brand new Nova, get a 272 + 250DR instead, a brilliant combo. For a pre-loved Nova alternative, get the SN2 + NDX.
The Bluesound is a way lesser solution while the qutest, although more transparent than the NDX, focuses on the hi-fi instead of the music (and you still need a streamer).
You really need to liten. The Nova sounds very different thank the SN3. I am not saying better or worse, but different. It really depends on your room and your speakers. In my (almost empty and large) living room with Harbeths it did not convince me, while the SN3 did. What I am trying to say is: consult your ears before you make your wallet decide.
I would take any Supernait in preference to a Nova for sound quality, although you lose a bit of convenience that you get when controlling an all-in-one. Pairing it with a Naim streamer helps as you can use ‘system automation’ to control the amp via the streamers control app.
Hm, and what about that gorgeous volume knob? 
OK, more seriously, here is my slightly longer answer too, should anyone want to read it - it’s a good question as in theory the ND5XS2 indeed looks better “matched” and complementary connected (as you say). However, I’ve had the ND5XS2 (before upgrading to the NDX2 after) and somehow, personally I never got quite convinced on the “engagement” side? It was good hifi. When I decided to try the Atom HE it was not even too much of a serious intent, more a curiosity. But I liked its character so much that it ended up in my main system too (I now have 2 of these things and believe the HE is one of those not entirely predicted special sounding models a good company does for the community once in a while :). I have not compared it A-B directly to the ND5XS2 or NDX2 but to me, although less refined (clearly) and detailed (may be but not much) than the NDX2, I feel the HE does offer a slightly better soundstage, more groove and, overall, a closer to a lifelike music experience, for me.
As for the gain you are right, I use the Atom HE at 50-80% and control the volume (and everything with one remote) from the Atom so I think of this as added convenience. I have tried to compare HE volume input levels further below as well and have not heard SQ loss. This setup allows my SN3 to stay at about 9-10 o’clock (rather than 7.30-8 which can be common with many sources including my TT). I have them connected RCA to DIN (Morgana). I think the HE preamp is actually very good and seems to work great with the SN3. In my case it also now all goes completely mellowed and totally lovable once through that SCDR (but it was added at a later point to replace the HCDR).
I did not even mention the top headphone amp that one gets but that should go without saying.
All that said, the ND5XS2 may be the more straightforward and preferable to the OP but to me the Atom HE gives you more (if slightly more expensive).
And just to be clear, I really don’t mean to bring any disrespect or disruption to the perceived Naim streamer hierarchy or to convince anyone to replace their NDX2 with an Atom HE but I feel completely settled and in a very good place with it.
Hi and welcome back.
Nothing much to add to what the other guys have said except that I’ve heard the Nova with speakers as good as the Titan 505/606 and Sopra 1s, and frankly it’s superb. Would I change my configuration for it, no because I love my TT and CDS3 but if I was starting now without a vinyl and CD collection?
Regards,
Lindsay
Great explanation! I do think it sounds really good as a streamer. I’ve thought about using one and the same way you are as volume control and streaming into a Nait 1. If it had a way to defeat the pre and use it solely as a streamer that would be cool.
I do actually use it also with a Nait 2 in the same way as with the SN3 (and this gives you a remote volume control for this system with a Nait too!), in a smaller room - very open, spacious and vivid sound (which they have in common) and good synergy.
Why not Atom HE into 250 dr instead of Atom HE into SN3/ Supercap?
Well, for one, the way it just happened was that I already had the SN3 when I tried the Atom HE, and not e.g. planning it the other way round - although indeed, I don’t see why it would not work well with a 250DR? I do use the HE with a power amp directly too (from Nytech) and they sound fantastic together when the Nytech puts in an appearance in my second system.
The SN3 also gives me the phono stage at present and it’s more than good too. AND now that I’ve heard it with the SCDR and what it does (for both the streaming and vinyl side), hm, I really don’t think I would want my SN3 or system to ever, ever be without this thing, it melts my heart. Actually I can’t imagine this being bettered by the 250DR with the Atom HE? So, I think I am ok:)
Should be interesting to try. Maybe at a dealer place?
Yes, and especially without the SCDR and some more demanding speakers. As always with the power amp side it’s a lot about the speakers, which kind of brings us back on topic to the OP question here.
Hi I’ve been down this very route. I found the Nova exciting initially but difficult to pair with my KEF speakers. Also found the sound a bit tiring after a while - ear fatigue particularly with vocals. I concluded it was a digital sound but very good on some tracks. I moved to the SN3 and an NDX2 and immediately felt at home as with the main system.
Part of the challenge is the degradation of sound a second system brings because the ears still hanker for the sound they recall as better.
I found harmony and happiness moving back to the separates and the speakers didn’t need changing either.
Best of luck with the move - go second hand if the budget needs that - even the SN2 with an NDX2 will bridge the gap beautifully I imagine.
I know what you mean and going between one’s main and second system can be fun!
My 2nd system is Atom HE into Nait2 or Nytech into a pair of Spendor D1s in a room which is 2-3 tines as small as my main listening room, and I must admit to very often having a hard time convincing myself that my main system is better! (although I know it is once I hear it again!:))
Just curious… How are you using the Atom HE into the Nait2? Does it have a ‘source out’, or do you still have to go through the two pre amps etc?
Yes, RCA to DIN with both preamps involved (the Atom has source inputs but not output)
Ah, I did think that that was the case re the Atom not having a source output - just wanted to confirm. For now, I’m doing something similar with my UnitiQute2 feeding into a Nait2.
Pretty much my experience verbatim
I see, great. Not sure what the pre-amp is and its control on the UQ2 (if digital?) but may be you keep it as high a level output as possible and control more from the Nait2?
Yes, I’ve done that as well with the UQ2 feeding into the Nait2 and just used the manual volume knob on the Nait2. Although, having gone back to the UQ2 as a stand-alone all in one for the last couple of days, and so having full App control once again, that facility is very nice indeed, even with a dip in sound quality.