Two Nait50’s here, both with turntables connected and no discernible hum.
U.K. based experience.
In the past I’ve had hum issues appear from nowhere on other amps and then either found other devices responsible (older TV for example suddenly putting noise into mains) or had to deploy some additional grounding measures.
yes.. i added shorting plugs and all quiet
Low level hum here (UK) but old Rega P3 from 1982 (upgraded 24v motor ) and I think rewired tonearm at the time. Soon to be replaced so we shall see if remains an issue.
All quiet here (UK) with TT connected, grounded power lead, amp always on and volume turned down. No additional ground wire with Mogami 2965 interconnect. Slight hiss as volume increases but not at normal listening levels. Vinyl all the way for me!
I had to resort to this. Not to get rid of a hum but a strange hiss/high pitched ‘sizzling’. Can’t really describe it. Worked and now only has the normal stage hiss when way turned up with nothing playing.
I’ve never had such a silent system as my Nait 50 + 333 + 555PSDR. I’ve had loads of different naim boxes and there has been transformer hum, always, and back ground hiss which was most present on 552/500 non DR. It’s interesting how much more relaxing the listening becomes when a system ONLY deliver music and nothing else.
Thank you all for the good tips and info! Some rca shorting plugs seems to do the trick. 
(I already had some rca ‘noise stopper’ caps, but they only shield the input from dust)
@Alco
Hi it’s not that it’s the way the input circuit works it’s noisy if not loaded as soon as you connect up it’s loaded and fine.
Earth or Grounding hum is very different.
Hope this explains.. 
Thanks very much Skeptikal for the explanation and reassuring!
Added spare Powerline to my 50, no longer needed in main system. Nice uplift. Not life changing. But noticeable.
Left field option and a little bit thin on the ground
Just to report that I managed to install a remote volume control for my Nait 50.
It works well, with reasonable steps from my mobile phone.
Now I am trying to code the robotic arm to obey the Naim remote, presently learning the Philips RC5 protocol.
Think of the digital noise that’s generating! What will that do to the sound? 
Roger
far easier and nicer to look to use the remote on my atom he for mine!
You are not Keith Richards by any chance are you?
@Rafael This is fantastic!
Right next, I want to see you programme it to change the input selectors
I will try Simon.
