My 552 uses input #2 for my streamer.
It can be accessed by 2 source buttons: cd and aux 2
If I wanted to use input #1 on 552 how to change inputs? When I used Narcom 4 program mode I can activate (light up) any input EXCEPT input #1.
Not that I want to change inputs, just curious why I can’t light up input #1.
Assume normal for 2 different source buttons to use one input (currently #2 which is default input for cd).
Note my only source is streamer.
Any advice on how to activate input #1?
David
Ps. Does anyone notice whether muting the lower record buttons result in any sound quality improvement?
Good thread - will be there I some hours/ days 
There is part at the end of the official manual
Maybe input is fixed.
How it is done with the input programming?
To be honest - the manual let me a bit feeling old when I read it yesterday 
From the manual:
Any NAC 552 source input socket can be selected by any button. For example, while the NAC 552 default setup is for the CD input button to select input socket No. 2, custom programming of input assignment could enable any input socket to be selected by pressing the CD button. Assigning of each record button follows the corresponding source button.
Input assignment setup is accessed through the NAC 552 program mode. To switch into (or exit from) program mode press and hold the prog key on the remote handset (in preamplifier mode). Program mode is indicated by a flashing indicator on the front panel volume control and the record selection indicators extinguishing.
note: If no function is operated within five minutes of entering program mode the NAC 552 will return to normal mode automatically.
Any of the six source buttons on the front panel can be assigned to any of the nine stereo inputs (seven DIN sockets and two RCA Phono socket pairs) on the rear panel. In program mode, as a source input is selected, a rear panel indicator will illuminate to designate the socket to which it is assigned.
To change the input socket assigned to a source button, select the source button and use the front panel record mute and mono buttons to scroll along the input sockets.
If the input socket selected is already assigned to a source button the indicator above the socket will flash repeatedly. It is possible to assign one input socket to more than one source button but NOT to assign multiple input sockets to one source button. The remote handset record mute and mono functions can also be used to set up input assignment.
To exit from program mode press and hold the prog key on the handset until the record select indicators are restored and the volume indicator stops flashing.
Table 4.3 illustrates the NAC 552 default input assignment.
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I had read the manual and saw all of this
When I scroll to the different inputs it refuses to light up input #1
No big deal since default #2 is fine
Thanks
In program mode press and hold DISP will reset your 552 to factory defaults. Do that first maybe?
Bruce
There is a school of thought that suggests input 2 is the best sounding input and that activating input 1 will make input 2 sound slightly worse. I believe it is something to do with location and length of wiring, this is according to my dealer anyway. However, I must admit to slightly preferring input 3 (the tuner input) but I must admit each input does seem to sound slightly different.
If you’re correct, and I have to rather doubt that you are, that would be worrying.
I’m not aware of any varying qualities of sound quality on the various inputs of my now very ancient, unserviced NAC52.
IIRC, I think input 3 was favoured open the NAC52
I know for sure that the tape loop/monitoring inputs are not quite as good on both the 552 and 52 as the other inputs and that muting the lower row on the furthest input from the one being used also results in a minor SQ improvement. I think the increases are very small but can be heard. I’d liken them to the improvement you get from turning the displays off.
On my 552 input 2 sounds a tad leaner than input 3, which has a slightly fruitier/fuller bass but that’s me on my system.
thanks all
I will stick with default input 2
System sounded great yesterday after slight adjustment of speaker position.
When system sounds good… don’t change a thing!
David
I don’t have a sheet of the replacement plastic input labels for my NAC52, so my OCD tendencies don’t allow me to switch between inputs.
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From a discussion on the old forum:
https://forums.naimaudio.com/topic.php?oid=1566878605984851&coid=159503632588890
It seems there was a time when input 3 was considered to give the best sound quality because it had the shortest ground path on the PCB, but apparently it varies with PCB revision.