The E boards gain are reduced by a factor of four .
I did some calculations with chatGPT and reached the numbers that S and K would have 60dB gain and E would have 48dB. I don’t trust chatGPT fully but so far that’s my best info and seems about right in reality. What we want to know though is something else.
In reality I think prefix E lacks dynamics with carts 0,3-0,4mV @ 3,54cm/s. Even though I really don’t need to pass 11 on the volume knob at 552. I recognize the type of limitations from my other phonostage which could be set at 50dB or 60dB. Everything gets much better with 60dB on my available carts. Those dynamics are important to feel and understand the messesge of the notes.
I think I just have to try to optimize the prefix first of all. The signal path has such ’integrity’ in this system, with a certain coherence and unison to it. Sounds mostly hit and miss at the moment though. Prefix was unused and 20+ years old, and don’t know if the aux2 was ever used on my 552 either. It’s been powered up 48hours (LP12 still on top of 500, which I don’t like at all, maybe a day or two more just to know more about prefix performance).
Prefix sent to naim next week and when I get it back I’ll soon change room (non-hifi related change). At that time I’ll mount the wall shelf so that prefix snaic actually will reach the 552 
I will try different positions inside the LP12 aswell, including ’Urika style’ on trampolin 2 if it’s possible.
If anyone want to share their experience listening Prefix vs Urika, please do 
Thanks Neil.
Expect lack in dynamics when using AUX 2 on the 552, go for a Supercap,is my advice.
I’m not sure “lacking” is right word here, as by any standard, via the 552 AUX2 the sound is superb, it’s just that the Supercap adds an extra dollop of authority and dynamics by comparison, albeit at considerable extra cost and an extra box (and Burndy cable, and i/c, and optionally an extra Powerline).
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Now when I get my converted prefix back from naim and go for the final fit I will really need to make sure I don’t compromize the performance of the LP12 by mounting a prefix inside also I understand there is compromises, but I want to balance them in favour of optimal music reproduction. I have some ideas I want to try mounting the prefix Urika style. I’ll do listening tests until I find the best solution.
I tried to do that actually but I’m not really sure about my different cards and how valid the test was. I have a confirmed 323/3 K set (which I prefer!) and a 323/2 set I think is ’S’ but I’m not sure. So there is both the difference in issues of 323 boards and the unconfirmed S. Here’s a picture, maybe someone can tell if the issue2 board is ’S’ or ’K’?
This setup has too much compromize, what I am hearing now hasn’t much to do with end results. What I noticed and I tried to describe is what you lose when you have too little gain for the cart in a phonostage. Something reminds me very much of using 50dB gain instead of 60dB gain with my other phono box used during this installation process. It’s not just ’gain’, it’s really a lot better music if you get gain right at phono stage, and I percieve the difference related to dynamics.
One of my favourite parts is actually it being powered by the 552. The ’integrity’ of the signal path is noticeable.
I think it has loosened and opened up a bit today. Sounds promising and I will give the prefix a go!
They both look like S Cards
You certainly need the right Prefix for your cartridge to start with,I was just pointing out that the Prefix is much better then what you will hear from Aux2 in a Nac 552.
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Fair enough - agree you need the same iteration of 323 card for any meaningful conclusions.
What? Actually I just googled resistor color codes and thought I just confirmed the one marked K is K 560ohm and the other unmarked was S 470ohm?
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I always loved the supercap of course 
maybe I should get rid of the 500 and use supercap for prefix and a NAP150x instead. Probably much better but the 552/500 is such a nice set 
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They both look like they have 470s to me.
The Left one is S
The Right one is K
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Since this thread might help someone else too sooner or later I want to share the quote from Julian Vereker about the s, k & e phono boards.
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Nice to know that my K17D3 Karat is less well engineered than those “Other” cartridges 
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The 552-powered Prefix gives a very balanced presentation (subjectively equally rolled off at both top and bottom) …but ultimately one that lacks lustre and energy. Even a Hicap powered Prefix is better than a 552-powered one. I know because I tried it out in an active DBL system.
A dedicated Supercap on the Prefix is immeasurably better yet-with great drive and inner detail that was just smoothed over by the 552-Aux.
When I did run a Prefix/Supercap, I used the only Din4-5 cable that available-the lavender one. These days much higher spec ones are available.
I have a feeling that the powered AUX on the 52 and the 552 are more of a convenience than an end-point. Even though the 552PS has a dedicated voltage regular board and a very large capacitor (?15,000 uF) dedicated the AUX.
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The Prefix was a decent phono stage in its day (basically a Stageline with a short arm cable and no case). I used a Stageline K for over 20 years powered by my 252 Aux 2 socket. A Prefix would be fine as a stopgap to your “forever system”. However, I think there are better choices available today.
(And I wouldn’t power a Prefix with a Supercap - I think you’d be you’re better off with a Superline and powering it with your 552.)
I wanted to ask that, why you did change from K to S with the Cartridge swap. Did you get the chance to hear the difference?
Maybe you actually would be better off using the K, on the basis that filters are more important than loading. Or is it Dynavectors have need for roll off?
It’s was Class A that did the conversion when I swapped my Troika for the DV cartridge. I always understood it was because the DV had a higher output and therefore needed an S Prefix. All this stuff about engineering quality is new to me.
Ed: Just google output and looks like Troika is 100uv and DV is 0.3mv