Ground on ND555

For the signal ground, when do you use default and when do you use floating?

Possible related question - does the answer change if using an ND555 with two PSs instead one?

Thanks in advance.

In a Naim system, the amp is grounded through the source. But you only want it grounded through one source, otherwise you may get a ground loop if two or more sources connect to ground.
If, for example, you had a Naim CD player as well, that would carry the ground, so you would then use the little switch to disconnect the ND555 ground.

What about a Superline as a source? Or a tape deck? Thanks.

Super line will depend on the the deck and it’s earthing.

A tape deck likely not.

ND555 / HDX, so streamer floating or not?

Martin Colloms says “Floating”, naim says “Default”.

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I would guess that it depends on what arm cart and how the signal earthing is connected up inside the deck. If in doubt, go by what sounds best.

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As the HDX was the equivalent of a CD player you’d imagine it would be the signal earth, so the ND would be set to float.

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HDX had a chassis/float switch because many had CD players in the system alongside.

If the HDX is not connected via the analogue out to the same pre-amp then it’s moot.

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I have a ND555 and a UnitiServe. Is that one or two grounding points?

It only matters with regard to sources connected via analogue interconnect to the Naim system.


Cheers Richard, that of course makes perfect sense.

Hi Richard,

The HDX only connects to the ND555 by ethernet cable via a Cisco switch, so no direct electrical connection.

I’m guessing the streamer should be set to default, then?


Is it measurable (i.e. check the din socket somehow?)


No idea, sorry.

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