For a while I ran my XS3 with a Stageline N, and compared between the two. There wasn’t a huge difference with my Goldring 1042 stylus/Roksan Corus body. I ended up running the Stageline most of the time but couldn’t categorically state I preferred it. In context in my system they were both “fine”
*I don’t mean to contradict you @IanRobertM! I doubt anyone has run through them all too, just wanted to write about the two I had compared 
You are not - IMO…!! You have compared 2 options - which I would consider both possible & likely.
But all 4… 
All I can contribute here is regarding the 3xx and 5xx series of Naim built in Phono boards.
I have used, in order - 322 N, 323 S, 323 K, 522 M, 323 E and 535 E (currently).
These were used in an NAC42 (original and -5 versions), an NAC72 (two versions, early & late), an NAC102 and an NAC82 (currently).
All have been Mostly Satisfactory… 
thanks guys - this is helpful. i wasn’t suggesting that there’s a 1-2-3-4 evaluation, more like what @gthack has said. if the XS3 and SN are based on the same Stageline circuit, stands to reason the phono stage itself would be comparable across the three. that point on why the 50 sounds different from @n-lot is also very enlightening for a non-electrical engineer like myself 
I seem to remember that they were newer designs not simply copies, and only slightly different between each other as the pics above show.
Don’t know about the NSC222 phono stage which also still has the traditional 470 capacitance-load.
The Nait 50 has a completely new design phono altogether (now at a modern 100 capacitance-load).
Very good point, also valid when the pre-map is powered by these three and the Stageline hooked up via aux2. Also the SN3’s phono will improve with the HC-DR it’s often paired with.
that might have been subliminally running in my mind when I started this thread…
Another random question…If you bought a Rega 3 or 6 would you go with their phono stage or a Stageline / Naim inbuilt PS like in an XS3 / SN3?
Assuming you’re going for an MM or MI cart, personally I would go for Rega’s. But that’s purely on the basis of what I wrote above, that the Naim ones you list will severely limit your choice of cartridges. Or at least impedance will be way too high for most carts optimum. I haven’t actually listened to any of these.
But if you go for MC or find an MM/MI cart which likes high impedance (and are happy to stick with such a rare cart in the future), of course it would be different.
Worth bearing in mind that the loading on the Stageline, while seemingly much higher than just about any cartridge on the market, doesn’t really restrict you to a tiny number of esoteric cartridges with high capacitance.
Even with a selectable phono stage, you tend to start with the capacitance setting that matches as a baseline for your cartridge and then play with other loadings to see which actually sounds better. In a lot of cases, the preferred loading selector on a phono stage doesn’t exactly match the cartridge. The 470pF loading was more an aspect of it’s design when making synergy with the Linn MM carts of the time (which also weren’t 470pF).
So it is definitely true that it doesn’t have absolutely universal compatibility, but it’s not as strict is needing a high capacitance cartridge either. All the carts that are known to have natural synergy with the Stageline like the Linn, AudioTechnica, Dynavector, and Sumiko have 100pF loading. All the carts known to have compatibility issues and not be natural matches, like Ortofon, also have 100pF loading. And even that’s subjective.
The real trick with the Stageline is to let a dealer guide you to a natural partner cartridge brand. You can’t match with anything like some phono stages. But you can match it with a lot. Naim knew this which is why they still went for that loading as recently as the still very new (in Naim terms) XS3 and SN3 amps,
yes, definitely MM. I’m going to keep it as simple as I can - nothing fancier than a P6, ideally an in-built phono stage unless the Rega option is the clear choice. @feeling_zen 's point on cartridge matching might be the difference maker depending on what I see offered.
I sold my Pro-Ject III yesterday so will finally get the Rega TT I want. Was a mistake not getting the P3 in 2008, but you live and learn…
One characteristic of all Moving Coil cartridges is their relative insensitivity to Capacitive loading.
So a High Output MC - such as a Dynavector - can work well with Naim phono stages.
While of course you’re right that someone might prefer the sound with a “too high” loading, one important thing to note is that you’re effectively changing the frequency response. You’ll have early treble roll-off, and a peak in response just before that. Well into the audible range with a capacitance that high.
While generally you’d want a flat frequency response, or at least I would. And as the OP uses sources other than vinyl, one could safely assume he’d have the same preferred frequency response curve for every one of them, and not have a different one for vinyl. So he’d be better off with an equalizer 
As I understand it that’s not entirely the case. High output MC’s will also be affected by the input capacitance, just less than MM / MI and more than LOMC. But I couldn’t say if 470pF would be an issue with the average cartridge or not.
I need an EQ now?? SMH…
Agreed. Ortofon’s popular 2M bronze/black (for example) specify a range of 100 - 300pF loading. The arm leads add about 100pF so another 470pF on top would be crazy and certainly sound wrong.
FWIW NA522 MM boards do not directly load the input with a parallel capacitor, instead (from memory) there is a 470ohm / 470pF low pass filter at the input. I’ve used these boards with a 2M Bronze and it worked brilliantly.
Just my 2p
Its all about the Inductance of the Cartridge and what effect it has, combined with the Capacitive load.
My understanding is this. Classic MM carts, like say a Shure M75, have a resonance which is in the high part of the audio range. The ‘right’ Capacitance will tame this.
MC carts still have such a HF resonance, but because their Inductance is lower, the resonance is at a much higher frequency, beyond the audio range. So they are less affected by Capacitance.
YMMV, etc… 
yes and the NSC222, but Naim finally moved to 100pF with the Nait 50 and the NVC-TT boards.
I agree with your general outline that the right pairings of phono board and cartridge should be auditioned (which alas is not so easy to do at dealers). From what I read here different ears prefer different pairings in different systems. Example the Linn Adikt with Naim 470pF phono in the Nait 2 was a big no-no here, somewhat better with the Nait XS3, yet others rave about the pairing.
So a lot of trial-and-error involved I’m afraid, but when you get it right for you it’s great!
This is my Japanese-built Ortofon ST-7 MC step up transformer between my LP12/ARO/Linn Troika and Nait50. A great little combo!
Interesting, I was also recommended the ST-7 over a Fono/Aria by my Rega dealer. I was told in demos many of their customers prefer the MC via step-up into MM over the MC phono.
All I know is that Ortofon has started promoting step-ups again for a while now for their SPU series. Available from dealers here so no need to find vintage ones like the ST-5 inlines and AT step-ups regularly depicted here on the forum. And that custom step-ups is a big thing in Asia.
I have not listened to them yet, how did you come up with the ST-7 @anon70766008 ?
I had bought an ARO which had been rewired and refurbished by Linn (not Naim), and it came with a knackered Linn Troika at no extra cost - a cartridge that I had always regretted not owning. I sent the Troika to David Giffin at Goldring to be rebuilt/refurbished, and set about finding a step up transformer, and I found the Ortofon ST-7 online from Japan.
It’s a fantastic combination.
