I am writing for advice because I have a big problem with my brand new Nac 552.
Today I connected the 552 for the first time with the Nap 300 Dr and N272 as a streamer source. I listened to music for about 2 hours (Vol 17) then pressed the Pause button on the N272 remote and went for an hour walk with my family after dinner. I was very surprised and scared when we returned home we heard a very loud noise reverberating throughout the entire floor of the house. It turned out that the right speaker Amati G5 was making a terrible noise. Pressing Mute on both the 272 and 552 did not help. I also turned the Vol knobs in them to zero, still nothing helped. The right speaker was making a very loud noise. Seeing no other solution I decided to turn off the entire system according to the Naim procedure. I checked the connections and cables, disconnected them and reconnected them. When I turned the system on again, the right speaker shot loudly and again there was a very loud hiss (I think at a level of about Vol 40). I was afraid that I would damage the speakers, I turned everything off again, disconnected the new Nac 552. I connected the Nap 300 to the N272 and breathed a sigh of relief because the system was working. I am afraid to turn on the Nac 552, I do not want to damage the 4-month-old Amati G5. Is it possible that the 552 preamplifier went crazy and turned itself on? Since 2012 I have had various Naim systems, both used and new. This is the first time I have had such a nasty adventure with Naim, which hurts all the more because it concerns the dream 552 preamplifier that I planned to grow old with.
Have you had a similarly adventure with a Naim preamplifier and how did you deal with it?
Sorry to hear this Oscar. I’ve not heard of such a thing, and certainly a NAC552 can’t turn itself on (it’s a hard in/out switch on the PS). I wonder whether the Burndy connector plug collars on the Burndy cable between the head unit and the PS weren’t quite fully engaged and there was a poor contact on one of the supplies or even the audio wires. Someone like @NeilS might have a better idea here.
How is the 272 connected to the 552? Using the line out, or through a unity gain input?
I’m guessing through a unity gain input on the 552, as you are quoting volume numbers.
Connect it via the line out RCAs on the 272 & through a normal line input on the 552. That way, if there is a problem with the cables, you will have control over the level of noise with the 552 volume control.
Regards
Neil.
Hope there is no damage.
@Oscar1974 Fully feel with you.
Unity gain could be tricky and Neil’s advice sounds very reasonable - hope this will save your day. Keep us posted.
Your profile says ndx2 - try him as source!
4 pin dn to 5 pin din.
But how to solve the problem that 1 speaker started to hum very loudly on its own. I will point out that the house was empty at the time, there was no one in it because the whole family was on a walk, I even left my phone at home connected to the battery charger.
No more NDX2. However… N272 was a trouble free source for 282 and 252 on the same 4 pin din to 5 pin din connection so I don’t see why it wouldn’t work with 552…
Have you tried another source - only for testing properly.
Have you done a reset of the inputs on 552?
Not your problem. It’s your dealer’s problem. Inform him ASAP and let him sort it. I would advise doing nothing more with the 552, just leave it disconnected. If it proves to be faulty then your dealer must either replace it with a brand new unit or refund your money - it’s your choice.
I suspect that 4 to 5 cable.
I’d recommend using the line out & use the 552 volume control instead of the 272.
Regards
Neil.
So moved and seconded!
+1 for an improperly inserted Burndy cable (this is easier to do than you think).
Do you mean out RCA on the N272 & input RCA into the 552 or input DIN 5 to control volume only from the 552…?
RCA all the way.
Din rhymes with Bin. 
Line out RCA sockets (you will need to enable line out in the analogue output menu on the 272).
You can use DIN or RCA to connect to the 552 (you may need to map the inputs accordingly).
The volume control on the 272 would no longer be in use with this configuration, so you can set the max vol to 0 if you wish. That will stop the numbers ramping up & down when using the remote for the 552 (assuming the 272 is set to the default RC5 code).
Regards
Neil.
Thanks for the advice, I understand.
But how do I connect the N272 streamer source to the 552 to be able to control the volume from the Naim app on the iPhone?
Another +1, double check the Burndies and all power leads and SNAIC.
You should be able to connect a lead (3.5mm mono jack to single RCA) between the remote out jack socket on the 272 to the RC5 RCA socket on the 552.
I haven’t tried this, but I think it should work.
Regards
Neil.
The culprit turned out to be poorly fitted plugs on both ends of the Burndy cable.
Quality control in Salisbury did not catch this.
Glad its sorted