I'm not sure how old your NAD is, but I had one of their integrated amps, 3240PE I think was the model number. The volume knob was getting scratchy, and shortly after I sold it, something went on the unit, possibly the caps, but I never found out for sure.
If you plan on keeping the unit it might be a good idea to "freshen it up", if only to keep it operating longer.
Ed
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