Loud Humming NAP200

I have a second-hand NAP200. A loud humming comes from it (the box, not the speakers) which is loud enough to be unpleasant and want to switch it off. The hum sounds low pitched, so I supposed that it might be a transformer hum. The repair person I spoke to said that it was due to dirty mains and that nothing could be done except getting a rectifier or putting the amp in a cupboard. The repair person was moving in a couple of says so he might not have been super motivated. Ideas?

Try a DC blocker, it may help. iFi Audio has one that many people rave about.

Mine hums naturally late at night and early Sunday morning when less devices are in use etc. so “dirty mains” is a bit simplistic. One that hums all the time may need to be looked at and serviced.

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Was that a Naim approved repair person…?

I have had my Naim units humm or buzz, but its rare - and only for a short time. AFAIK, it is often due to ‘dirty’ mains - harmonics on the mains, caused by some domestic appliances. I recall hairdryers being a suspect…?

Both my NAP 250s used to hum.

If there is no hum coming through the speakers then it is usually DC on the mains.

As others have mentioned, a DC Blocker may work.

I fitted the IFI DC Blocker and the hum instantly stopped. More importantly, there was no detrimental affect on the SQ. So can happily recommend this.


My 300 was like that last week it was a loose banana plug.

I also have this even after full service. I’ve been recommended the Audiolab dc blocker for £100 but some say it may not fix it so to buy from somewhere you can return. I’m ordering from richer sounds today as the local independent shops I’ve tried either haven’t stock or don’t particularly want it returning. There’s a rave review on you tube and many agreed in comments.

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Mine used to do it, occasionally for 30 seconds at a time, never bothered me, thought it was just something they do. Current 250DR does not buzz

I had the same problem with my NAP 200. I bought a Audiolab DC Blocker which reduced the hum but didn’t remove it completely. I can still hear the hum two meters from the amp.

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There is an extensive pinned thread in the FAQs on mains hum.

A good starting place

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Might this work? Seems reasonably priced. Fruman AC-210 A E Compact Power Conditioner. Online in Australia. Anyone had experience with this bottom-of-their-range power conditioner?

I wonder if this would work? It’s just a DC blocker.

I would personally try the Ifi one or the Audiolab blocker first.
I think the consensus is conditioners are best avoided.

I presently use two of these and they work very well.

Totally stopped the humming with no detrimental effect on the SQ.


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Hi Neil I took delivery of audiolab dc block yesterday and plugged the hicap in via it. We’ve so much plugged in it’s a bit of a minefield so thought I’d try one. The humming has greatly reduced. Even on my 180 even though the blocker is connected to the hicap. I haven’t really noticed any difference in sound quality but keep checking - plugging and unplugging so using with or without. I’m now wondering whether to try another on the 180 see if this will totally irradiate him as it’s still there just greatly reduced. I’m wondering about your comment though - ideally should be avoided - is this a definitive or can they work positively as mine seems to (obviously there’s comments for and against but there’s a lot of positive reviews) even though I can’t tell any difference I’m unsure whether to try another. Going round in circles a bit mentally !

I’ve tried on my hicap with positive results and no obvious detriment to SQ. Thinking of trying another on my 180… just responded re others negative experience. I can’t notice any deterioration with one plugged in?

Conditioners are different to DC blockers. I think DC blockers can work, I use one to great effect on my XS3.
I’m pleased the Audiolab unit has greatly reduced the hum.
That’s probably the best you can hope for in the circumstances but ofcourse its best to actually identify and, if possible,remove the cause of the hum, which will be DC on your mains. The thread mentioned above gives advice on that.
Re conditioners, they are different beasts altogether.Ive not had cause to use one myself by my understanding is that Naim advise against their use and some members have had negative results with them.
@Richard.Dane im sure will be able to expand on this topic.

Yes, I’ve posted on many occasions on this topic re. Naim’s experience with testing out various expensive conditioning devices at the factory; AFAIK, the advice is still to avoid unless absolutely unavoidable.

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Hi Richard Are you classing an audiolab dc block as a conditioning device ?