There’s your problem right there.
Aggressive hoovering can ruin the quantum balance of the cables. You have probably broken a nanoparticle lattice resulting in the electrons losing their alignment…
Stick to dusting.
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My comment was more related to me only having 5% of a scooby what you’re talking about.
Hmm?
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Does the hoover sound better with the hi-fi disconnected?
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Did you manage to cure the problem?
Rather than shit on another thread, having just read Paul’s thoughts here
I thought I’d pop this one back open.
Hum is still there. There is definite mileage in Ed’s theory
that the shitty Sonos box is mostly responsible.
Basic observations, volume at 12 o’ clock so music would be put-you-out-of-the-room loud, by “connected” I mean plugged in with RCA phonos
- With the Sonos box on, on the “stream” channel to which the Sonos box is connected, the hum is very loud
- With the Sonos box on, on any other (disconnected) channel the hum is even louder
- With the Sonos box on, but disconnected, there is a small background hum (you have to put your ear close to a speaker). So it’s not that the wall wart is fucking up the mains in general or transmitting nasties through the air.
- With the Sonos box off, but still connected, the same result - a small background hum
I know fuck all about this, but the problem is clearly when the Sonos box is both on, and connected.
Any suggestions other than buying an ND5 XS 2, or a DAC that would effectively isolate Sonos from Naim, or a new amp (yes, yes, ho ,ho)?
Might this
(taking a lead from Paul’s suggestion of the DC blocker) make a difference? £129 is a bit of an extreme punt.
Thanks in advance.
How are you switching the Sonos box on and off ? Are you doing it using an On/Off control on the box, or are you doing it at the mains switch to the wall wart ?
Does the wall wart have the ‘Class 2’ square-in-a-square symbol on it, as here
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This way.
Yes - I’m currently googling what that means 
Simplistically, Class 2 devices have very high quality insulation between the mains supply wires that go into them (Live and Neutral) and any wires that come out of them i.e. the ones to your Sonos box, or any other metal parts on the outside of the supply. If devices meet this standard then the manufacturer doesn’t have to safety-earth them, so he can use a two-core mains lead. This can help a lot if he’s making a product which will be used worldwide, including in countries where the safety earthing at the supply socket might not be nearly as good as it is in the UK. Two-core mains wiring is also a bit cheaper.
Perfect insulation stops any current at all from flowing through it. Or, more exactly, any DC current. But the mains isn’t DC. It’s AC, and AC can ‘flow’, to an extent, through anything (even a vacuum). So the safety standards have to permit a small amount of AC leakage current to flow. And some manufacturers of (transformerless) wall warts use this permission to get away with some low level of connectivity between the mains wiring and the supply’s output wiring. Sometimes, if they do this, they leave the Class 2 symbol off the device. So if you’d said there was no symbol on yours then I would suspect that that could be the problem. But you have found the symbol. So now I can’t be sure.
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I understood most of that, so I think I deserve a nice G&T 
Thank you.
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OK, I actually googled this and as ever there’s a weird little Sonos/Naim/hum corner out there.
The consensus seems to be, as everyone is hinting here, two pin mains on the Sonos and odd grounding arrangements with Naim.
The “solution” is
The wire is on the outer ring of the RCA.
Plug into a spare socket on the Sonos (i.e. the rubbish / useless phono ins), and allow the Sonos to ground to the mains earth.
This all looks quite deathy to me.
Pretty much the same as an ESD plug (Which ca be had for next to nowt)
Sonos don’t use external wall wart, it is a mains cable directly into the unit.
Must be class II though as they are figure of 8 two pin power cables.
So this
and this
aren’t a 12v 1A wall wart, they’re just a figment of my imagination.
Phew, that’s a relief 
Ah, didn’t realise they replaced the Connect or ZP with a new Port thing.
Tried the Connect years ago but it had issues locking to the DAC, convenient but the builtin DAC was shit.
I’ve got a Bluesound Node 2 if you want to try that (has a 2pin fig8 power cable)
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Ought to work. Personally I’d find an older style mains plug where you can pull the earth pin out completely. I’d connect the green/yellow wire to that and push it into the correct hole in the mains socket. That way if the wire should get yanked it will probably just pull the pin out of the socket. If, instead, the wire does come out from under the screw on the pin it won’t have bare live metalwork in quite such close proximity.
If you want to use both the input and output phonos on the Sonos then you could just earth one of the outers using a small croc clip. It’s not a safety earth so it doesn’t need to be very robust.
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It’s always worth bearing in mind that once a system is wired together, the possibility always exists (no matter how tiny) that a fault anywhere in the system might render every metal surface in the whole system Live. 0.1A can be fatal, even at just a handful of volts, and as the old saying goes - it’s going to hurt the whole time you’re dying…
Others may read this and decide to try something similar in their system, and in doing so provide a nice new shiny low-impedance shortcut to Earth for a fault state anywhere in their system. The possibility then exists that fuses, RCDs &c may be bypassed, increasing risk exposure.
For this mildly-neurotic reason, may I suggest a current-limiting resistor be included in any system-ground-to-mains-earth strap-on as a matter of general principle. I’d agree that in this instance it’s almost certainly never going to be justified, but should a fault state occur where decent amounts of current are finding their way to Earth undetected, a current-limiting resistor limits potential exposure and means conventional safety features are much more likely to do their job.
This is why I (and others) suggested ESD plugs - 1M is mighty, but still effective for this purpose (problems usually underlying system noise are typically in the milli- or even micro-volt/amp range, so don’t need a low impedance connection to Earth IME), and should something ever go tits-up, insurance investigators are a whole lot less likely to fuck you off than if they find a lashup bodge…
And yes, I’m aware that every generalisation I’m making has a suite of exceptions - but if in doubt, choose safety every time.
Personally, I’d also fuck-off the wallwart and replace it with a quality linear PSU. Switchmode PSUs are much, much better than they were 20 years ago (thanks to EU ESD legislation…), but they are often still crap - too often underspecced and prone to short lifespans.
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Yes, I looked at the usual suspects.
The linear PSUs all cost more than the original component.
I’m struggling to think of a scenario where that could generate an electric shock risk (pretty much by definition the low-impedance short will short out the voltage which would otherwise have shocked someone) although I think I might just about manage it, given long enough. But it’s very easy to imagine that it could short out fire risk protection. In some ways fire is a more serious problem. It can kill lots of people (Grenfell, dear God) and it can happen with no-one there and perhaps late at night.
Of course any significant mains current flow in an earth conductor should trip either an earth leakage detector or, these days, an RCD, assuming the consumer unit’s got one.