Hi. I have a NAC 552, NAP 300, NDX 2 and Sopra No2. I’ve thought about automating the NAC 552 by utilising the RC5 connection between NDX 2 and the NAC 552. I’ve tried it briefly and it works fine controlling the volume.
My question is this: Is there any sonic downside in using the RC5 connection? Thoughts please. . .
Not that I’m aware of. I imagine that if there were then Naim would not have offered the facility. Performance is always the highest priority.
Thanks Richard
I have read on the old forum that RC5 does have a negative effect. The thread went into a lot of detail, I believe @Darkebear & @Simon-in-Suffolk were contributors. If I remember correctly it was agreed to be true of the classic preamps such as 552 252 282. What I do know is it does not affect my Supernait because its RC5 circuit is isolated
When I last heard it - it did. It took the edge off clarity for me.
Easy to try - play music with connection then with it pulled-out and decide which you prefer, or if no difference for you.
For me it was enough that I’d always insisted in any demo it was removed as I found it really annoyed me to have performance blunted for no great reason - I can use the remote and can remain in my seat and putting in RC5 meant I don’t need the remote and can use the slider on ipad and get poorer performance - crazy given what you have spent on getting 552 - IMO of course! 
On the 252 it is a small effect and on 552 somewhat larger - unless Naim have fixed it all and it is now fine. Last time I checked my Dealer always pulled it out for top-end demonstrations.
DB.
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I never noticed it when I had it on my 552, but then I never did an A-B comparison, so thank you Mike and DB for chiming in and giving your opinion that it might affect performance. I must have forgotten that old discussion…
In the end though I only had it connected briefly as I preferred the tactile feel of just using the Flash or R-com remote.
It might be different with the new streamers, the OP has NDX2, DB is ND555,
S-i-S (if he chips in) is NDX2. It will be interesting to run a test on the new streamers.
A high quality shielded cable is mandatory for this automation. I tried a cheap $2 cable and found it degraded the sound… once I replaced it with a shielded cable I did not hear a difference. It was not terribly expensive but it took some research to find a custom cable maker.
Everything matters.
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Interesting, my dealer said it does downgrade quality, but it is convenient. Will look at a shielded cable.
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Chord are missing a trick here…
@ChrisBell I would be interested to hear the make and source of the screened RC5 automation cable you are using. I have always had a cheapie version and have overlooked this since upgrading to a 552.
Likewise @Gazza, if you find a screened version of the RC5, please let me know.
Audioquest have a few, not sure if they are any good…£31.50 upwards on that shop in the future in the UK. So yes Chris any tips other than not using automation? Maybe Belden have something?
Or perhaps Nigel you could try the Audioquest Yosemite or Angel and let us all know😁
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I use Audioquest Ethernet cables and have some respect for them but £31.50 for a shielded RC5 is a bit rich, even for Audioquest.
I’ll have a look too but if anyone comes across a shielded RC5 at a more reasonable price, please let us know.
I’m sure there will be a suitable one that meets requirements: must be satisfyingly over £1k to inspire confidence it will work IMO. 
DB.
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I raised this some years back too as I felt it had a detrimental effect.
G
I had noticed a slight impact on my 252 with my NDX, but I have not noticed any real difference on my new 552 with my NDX2… so I keep it in as the benefits outweigh any possible marginal impact…
Now I do use a different cable now…so there is always a possibility it’s the cable… but I kind of doubt it would have any meaningful impact, and no real curiosity to fiddle around…
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The Cable is Belden 1505F. Ram Electronics sells a SPDIF cable, 3.5mm to RCA for $23.00 here in the US. It was recommended by Chris West from AV Options. Does not detract from sound quality that I can hear.
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Nigel,
audioquest makes coaxial 75 ohm cables , from cinnamon ( 60 euros), to carbon and also coffee ( 470 euros).
the cinnamon should be enough probably.
Looking at pictures of the internals of 552, 252 etc & the RC5 connection point, I really don’t see a need for a ‘special’ cable, internally the outer goes to gnd & the inner is a single wire a few cm long going to a PCB.
It’s much the same inside an NDX.
As for a screened / shielded cable, cables I’ve seen on www sales sites are coax, so what is meant by this shielded cable & what does the shield connect to?
Indeed I understand the automation physical interface is name proprietary. Certainly there is no mention it is a 75 ohm transmission line and so 75 ohm CI cable although would work is unnecessary .
I understand there was an issue a few years back on the serial line voltage levels, such that the automation master wouldn’t always drive some older Naim devices, but I think Naim can modify the receivers if an issue, I’m sure Richard Dane can provide more info if required.
I use a mono 3.5mm to phono lead… I think about £5 off amazon and it works with no meaningful SQ impact that I have noticed…
Now a gripe, the new streamers only have one automation out, as opposed to the legacy streamers such as the NDX having two … so before I could automate my NAC and CDX2 … now it’s one or the other, and so I put it on the NAC.
One rainy weekend I might make and try a splitter.