Stay away from the nad

djengan,

I suspect that the problem your having is simpler than they say.
Two questions:
Do you live near salt water?
Do you own a tape deck?

The description of the problem does not suggest that it is serious.
I'm guessing you don't use the tape monitor switch. It will eventually cause the audio to "drop out" or drop in volume if it is not used especially if you live near salt water. 

The cure:
Exercise the tape monitor switch a few times and see what happens.
If there is a "tape 2" switch - same thing.

Hope this helps
Roger

Hello Everyone i do like this site a lot 
I've had NAD's for a long time myself i stared off with the 7600 Receiver and the 2600 Amp with a pair of SDA Polk Flagships i think it was inn the 90tee it sounded great the Amp where strapped i guess that was the word used at that time.

And now i have the same Speakers but with pair of S 200 and an S 100 Preamp they all have done me great 

I guess my point is things can happen to any kind of Electronics NAD we make it right i believe
Thanks to all here 

People love NAD your breaking there heart oh boy!!

It has a built in timer :-)

Over the years I've owned several NAD components, back to the 1980's and have had minimal problems with the brand.  A receiver I bought years ago had that same problem (one channel suddenly about 25% of the volume of the other), and my M5 Masters Series SACD player had a transport failure (wouldn't open the tray), but other than that, good service from NAD components.
Having said that, I understand that NAD was one of the first audio companies to outsource their manufacturing to "contract" builders.  It would not surprise me that, if you opened two of the same model that the components would be from different suppliers.
I have since upgraded to electronics designed and built in the USA (McIntosh & PS Audio)...and so far (knock on wood), haven't had service issues with either brand.