Naim 5si hum / Sonos ZP90

Hi Arnoud,

What else (if anything) do you have in the system other than the Sonus ZP90, phono interconnect leads, the Nait 5si, speaker cables and a pair of speakers?


I have nothing else in the set up.

If you use non grounded wall connections then try to change direction on them. This is totally critical in my setup. It goes from humming a lot to nearly silent if I do this correct on all products. I’ve noticed Naim products are not that well protected against DC level on the AC input which you often get into your system these days.

Hi Slamdam,

I ve already tried that, and no result. Would really like to know what the 100% effective solution looks like.

Have you tried the ground wire trick? I would guess it’s being caused by the floating mains of the Sonos finding a root to earth via the signal connection to the earthed NAIT. As such, if you can give it another route, that may help, or it may not. Alternatively, you could use a ground loop isolator on the RCA phono outs of the Sonos. Or, possibly the best solution would be to use a decent DAC and connect via optical between the Sonos and the DAc and then analogue from the DAC to the NAIT.

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Hi Richard.Dane,

Can you show/teach me in detail how the ground loop wire trick works?

In my topic-opning i posted some questions:

-what type of wore to use?
-how and where to connect exactly (photo’s?)?

Thanks a lot,

Hard to say as I don’t know my way around the Sonos unit. I’d be looking for maybe attaching a thin piece of hook-up wire from something like the metal chassis of the Sonos to the earthed screw under the NAIT 5i

I don’t know. Hopefully somebody can show some pictures of what a working solution looks like. Thanks in advance,

I suspect the issue here is a lack of signal to mains earth connection and possibly some leakage current finding it’s way to the Nait from the Sonos. The Nait doesn’t have a signal to ground connection by design and would normally rely on a Naim source component to provide this. The ZP90 / Connect is double insulated / 2 pin connected to the mains supply.

I would make up a length of wire with a phono (RCA) plug on one end and an earthed mains plug on the other (I’m assuming you’re in the UK…). Connect the Earth pin of the 3 pin mains plug to the outer of the phono plug and plug this into one of the spare phono sockets on the Sonos (you should have a spare pair of input sockets). This should cure the hum.

Hi James,

No, im in the netherlands. Having a hard time placing the instructions. Can anybody visualize? Thanks,

Hi Arnoud - ah ok. I’m not familiar with the mains arrangement there - do the wall sockets provide a safety Earth connection ?

I’d suggest if what i’ve recommend needs further visualisation then i’d seek advice of your dealer. I wouldn’t want you making a wrong connection to a mains socket which could cause damage or prove lethal.

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Was it not that one could make a wire from the metal outter of a empty din-socket to…?somewhere on the 5si?

If the metal outer on the DIN connects to the chassis but on the 5Si this isn’t the case as the connectors are mounted to the main PCB - You’d need to connect to a case screw on the 5Si as the 5Si doesn’t provide a convenient earth post.

Richard makes a good point above - use a ground loop isolator (in this case it’s not a ground loop but the method is the same) between Sonos and Nait or even better, use an external DAC - the 5Si is a great little amp and the external DAC would be a big step up on the Sonos analogue output.

Hi James,

No, i prefer not to add extra items into the system.

Would connecting another, earthed device cure the hum?

Hi Arnoud - The simplest solution would be connecting a wire to mains earth as mentioned above. I had a similar problem with a Sonos Connect and my Naim Nait 1 in a second system i was playing with and made up a cable to cure the problem. I may still have it in my spares box so i’ll take a look later and if i find it take a couple of pics which should give you an idea of what you need…

This could be worth trying. Naim amps are grounded through the source, which could be a CP player or streamer, so if you connect a source to one of the inputs, it could solve your problem. Make sure it has a 3 pin mains connection to carry the ground, unlike your Sonos.

Here you go (UK Specific) - Plug the mains plug in to the same block as the amp / Sonos. Connect the RCA plug to a spare socket on the Sonos.

You only want to connect to the outer ring of the RCA connector. Leave the inner unconnected.

Connect to the earth pin only on the plug - this is a standard 3 pin UK mains plug. This will differ for you as you are outside the UK

As i said before, if you are still unsure, especially about the mains earth then seek local advice or as Chris suggests. add another source that does provide a signal earth to mains earth connection.


Thanks a lot James! It worked like a charm, no more hum to be heard !


That’s good news - glad it worked out.


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