Urghh...NAC 552 burn in rollercoaster

My new (to me) 552 DR seems to be going through another ‘shrill’ stage at the moment, which is typical now I’ve got an hour or so to sit down and listen! Fleetwood Mac’s Rumours last sounded beautiful on my 282/ Supercap DR but I’m having to keep the volume low or it’s too “shouty” through the 552 at the moment.
I purchased it recently and it went to Naim to for both the head unit and power supply to be fully serviced and the head unit additionally had a new volume pot fitted. It came back a little over two weeks ago. After a few hours warm up, I had about 36 hours of utter joy and then the rollercoaster started! Don’t get me wrong, there have been days since when it shows true moments of greatness but typically when I get a moment to enjoy it, it’s having one of its ‘turns’! I guess this may be exasperated by having both units serviced at the same time, so I’m trying to be patient - after all, it’s only been just over two weeks.

Having searched the forum, there’s not much about the run in characteristics for the 552, or the time it takes for them to disappear. When my 282 head unit was serviced last year, it didn’t seem to manifest the same issue, just got subtlety better over time, so I guess the power supply has some effect here?
Anyway, just wondered if other 552 owners have had a bit of a rollercoaster ride with their units running in too, whether from service or new?

Yes, I’m afraid that the burn in period is a bit of a pain in the proverbial. My dealer told me not to make any evaluations on SQ for at least two weeks after mine came back from a service and DR’ing. He was dead right. It was up and down like a donkey’s gallop! From switch on it gave me a glimpse of what it was like. The following day it was as flat as a pancake and just plain dull. The next day it could cut glass. I had to give up listening as my ears were bleeding. This continued for several days become less obvious as time went on.

Then on about day 15 it just suddenly snapped into focus. Like someone had pulled a switch. I remember being amazed at the sudden jump in realism. The system was no longer playing it CD it was playing live music in my front room. I’d heard it mentioned that there was a further lift after six months or so and I experienced the same thing.

Just make sure you get the power supply away from the pre and the cables are well dressed. Then sit back and enjoy the wait.

I’ve had a nightmare with my 552, back to HQ for the 4th time!
Every time it has been back and returned the burn in period resets - blooming frustrating as I keep thinking is this burn in or an issue. It’s been critical for me to have fantastic dealer support (lent me their demo 552 whilst mine was back at HQ!)

Good luck with your burn in - feel your pain!


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Hi Geko, thanks for the info. I’ve got a brain and brawn stack to keep the power supply separate, so hopefully, once things have settled down, it should benefit from that. I’m looking forward to when that ‘switch’ flicks!

Thanks Gary. That’s a really poor show that yours has had to go back that many times; I hope you have it back now and you’ve got the perfect example. Like you say, it’s times like that when a good dealer is worth their weight in gold… but four loads of run in… I feel your pain too!

2 months - better

6 months - amazing



Hehe, thanks Chris. I suspected this would be the case, a couple of weeks would just have been too easy wouldn’t it :wink:

Not sounding too bad today, not as harsh as yesterday… who knows what tomorrow will bring!

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The OP’s experience sounds very similar to my experience when I changed from a 282 to a freshly serviced 252. I know the 552 is a different beast but I suspect the principles are the same.

There’s more here https://community.naimaudio.com/t/252-sound-signature/15297

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Hi trickydickie,

Yes, I’ve read your thread with interest and can relate to your experience of moving from 282 to 252. I bought my 552 having come fresh from service at Naim, so I never heard it beforehand, but it came as a bit of a shock to me to be honest because the 282 didn’t exhibit the same (quite horrible) issues as the 552 when it came back from service last year. In contrast, the 282 just sounded nice when it came back, then continued to improve gradually over about 3 months; whilst it improved with time, it never sounded ‘off’ at any point.

Clearly the 252 and 552 differ from the 282 in this respect and need time to settle down. I suppose there’s more going on inside the 252 and 552, so it stands to reason that when there’s more being changed inside, there’s more to sound different and acclimatise again. That’s my rationale for the differences in the run-in effect anyway!

Meanwhile, I was pleased to read that things are well on their way to where they should be for you now, and I suspect you still have some incremental improvements yet to come. As I type, I’ve just sat down and had another quick listen to the 552 (for the first time today), it’s definitely sounding sweeter again tonight… progress :slightly_smiling_face:

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In my case, the dealer’s demo 252 was in a different league than my new one, but the new one was not horrible and improved gradually. I never had this big wow moment, but it’s wonderful now, I have had it for 6 months. The 300 was a rollercoaster though and had moments when is sounded positively broken. And in this case there was indeed one defined moment a few months in, when I felt that everything had suddenly come together. So if this is an indication, look forward to it.

I think there are some Tantals within the 552…
Those little stuff needs time to running in…
There are for example more than 50 in the headunit of the CDS…

I had to wait 18 months for a serviced preloved 552/500 to come together!

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18 months - noooooo don’t tell me that!

Hi Jason, I’m afraid the higher up you move with Naim gear the longer the run in period takes. Usually a 552 levels out for peaks and troughs within the first 4 weeks and beyond that it incrementally improves over time 3-6 months or in my case beyond. Patience is a virtue in this case, however enjoy :+1:t3: Peter


Thanks to all for your observations on this.

Peter, I think you’ve probably hit the nail firmly on the head there, as it now seems I’m finding out!

Anyway, thought I might periodically report back when I remember to do so, just for anyone else going through the process, as I didn’t find much about 552 run in when I searched.

With that in mind, it will be 3 weeks since power up tomorrow and things have taken a real leap forward in the last 24/36 hours. Going back to Fleetwood Mac’s Rumours, which I’ve kind of used as a benchmark each evening, reveals a real progress… it’s no longer ‘shouty’, the bass has tightened and I’m hearing real textural qualities to voices and instruments… this is more like it! Watch this space…

… well Jason, should be onwards and upwards from here on! :partying_face: Enjoy Peter

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Just an update, as promised, for anyone who may be interested in how the 552 is settling in…

I’m now 7 weeks into enjoying the 552 after initial power up; it has not been powered down at all within this time. So, after the first 3 weeks things started to settle down, having had a period of sounding great for the first few hours and then 3 weeks of unpredictable swings between ok and awful shrill edginess!

Beyond around 3 weeks it has been fairly consistent sounding, more like a grown up 282 but still with a slight ‘lisp’ in the higher frequencies. Last week (week 6), I sat down after 3 days of not being able to listen to the system, as I had been particularly busy and simply had no time. When I did eventually get a chance to play some tunes, things had taken a real step forward. Scale, refinement and detail had all stepped up significantly, and the ‘lisp’ was pretty much gone. It was nearly as though someone had swapped out the unit for a run-in version… I didn’t get much else done for the rest of that day :wink:

Now I get what all the fuss is about; this is an extraordinary pre. Hard to believe it may improve on this… let’s see.


Theres no see about it, it will get even better. Had mine for ten years now and it still makes think “wow” at times, infact a lot of the time. :grin:

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Looking forward and thanks for the heads-up in this thread. I bought a new 552 and expect delivery in august.

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I do find these stories about rollercoaster rides with new Naim kit strange as I don’t think I have ever really noticed any difference in presentation from out of the box until today. I’ve had a new 552. It sounds as lovely today as it did on day one.



All I can say, is that if you bought a new 552 and you’ve now had it for some time and never heard any difference during the the first few weeks, then I’m dumbfounded! I’m not sure why two examples should be so different?

What I would say is that I have never experienced anything near the same level of change with the other Naim equipment I’ve owned over the years and run in from new or service. I’ve heard subtle changes, yes, but nothing like the changes I’ve heard with the 552; it’s been unlistenable at times and I’ve walked away from it… shrill and piercing in the mid and high frequencies. Now that’s gone and it’s just sublime. Can’t tell you why, I just know that’s what I’ve heard and nothing else has been touched or changed.

Strange eh!