Hum is doing my heid in

Ignore my suggestion as you’ve already got another source that can provide this link. Just for completeness, do you have anything else apart from the turntable and ND5XS connected to the SN2 ?

@james_n Yes, a CD player. But even when I remove the streamer, the CD player and a nearby modem, the hum persists. I went a step further and disconnected the LP12 as well. As long as the interconnects were between the SN2 and the P75, and the power is on, the hum remains.

I keep coming back to the interconnect and the PSU, but my knowledge of grounding is is basic as can be.

Not particularly, just worth trying some different ones as it may cure the issue - I’ve had similar in the past and a change of i/c did the trick.

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Ok if the hum is still there when all is disconnected, other than the P75 then it sounds like the issue is with this unit, or indeed its PSU. Can you borrow a replacement from your dealer to check ?

That’ll be my next step. I’ll try to get hold of another (better) interconnect too.

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That sounds very sensible. Hope it all works out :smiley:


Would a DIN to RCA generally be better than RCA to RCA?

AFAIK, Naim doesn’t make DIN to RCA anymore.

Just a thought. Is the power supply for the P75 double insulated? Does it actually have a mains earth connection?

Can you reverse the mains plug polarity?

(Sorry - not familiar with US electrics… )

Possibly. Try it.

The joys of spill chucking , you aren’t the fist and you won’t be the lost

@AndyR @Richard.Dane I really don’t know the answer to those questions. I suspect it might be possible to find a double-insulated PSU with a mains earth, but reversing polarity?

I had a similar problem with the SM PSU’s creating hum in odd inputs on my Rotel Pre.

What power supply are you using with the P75?
If it’s only got two mains pins, can you plug it in the other way round?

(The manual suggests it should be completely immune to all this, but… )

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How did you fix it (assuming you did)?

@AndyR I just tried that, but no luck. I’m planning to test, in this order, interconnects, a different PSU, the P75 Mk. 4 and the Stageline. It’ll take a while to get those tests set up.

Meanwhile, I changed the P75 settings to Phono Enhancer mode, which means I can listen with the volume at 9 o’clock, and hence have less hum.

Good to hear, I had wondered about that. It’s a while since I replaced my P75 so I don’t know how relevant this is but are all the jumpers in the right place for the Troika’s spec?

Yes. I enlisted my wife, who is much more careful and attentive than I am.

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When I had a P75, I experienced extraneous noise in PE mode…this resolved when switching back to non-PE mode. Incidentally, in PE mode my initial thoughts that the sound was very exciting…on switching back to non PE -mode, I thought that the sound was more natural.

Interesting. I’ll try reverting after a day or two of listening and see whether I experience something similar.
Did you upgrade to the Aura in one step, or did you try another phono stage first?

…I upgraded from the Mk 4 version in one go. Make no mistake, the P75 is very good…but I am astonished by how well worth it the upgrade was.

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