Audio Systems: Home stereo static, nad amplifier, yamaha tuner

Question
QUESTION: I own an old NAD amplifier and have connected to it a Yamaha tuner, an ipod and a Sony CD/DVD player.  Completely out of the blue we started hearing unpredictable waves of static and crackling. There seemed to be no obvious cause and it did not matter which of the inputs was connected.  The main speaker out goes to a Monster Cable switcher to three sets of speakers on the lower floor. All three sets are affected so it does not seem to be a speaker issue.  I took the setup apart and tried out the amp on its own with the speaker switch (with an ipod) at A or B and ran it for hours with a test speaker with no problems.  I tried different input jacks for the ipod and again no problems.  When I hooked it all back up I had the same intermittent problem...  Oddly the sound continues for 4-5 seconds even after I power off everything.  Any help would be appreciated as the sound is awful and I don't even know where to begin.

Scott
Toronto

ANSWER: You may have a floating ground somewhere, but more than likely there is a component breaking down in the "front end" of the amplifier.  What model of NAD do you have?  Please post the serial number as well as NAD sometimes changes the design for a model without changing the model number.  These changes are tracked by serial number groups.
Thanks,
Dan

---------- FOLLOW-UP ----------

QUESTION: The NAD is model #3240PE abd the serial is D324003631.  I should also mention your floating ground theory might be accurate because it often happens when I start touching some of the wires and cords... thanks in advance.

Answer
This model is known for bad caps as well.  This unit should be sent to NAD for an overhaul.  All of the caps in the front end should be replaced.  Doing this now will prevent more drastic problems in the future.  Check with NAD for an authorized service center.
Dan