Weird Amp Hum - Intermittent DC on my AC line?

[Shayne]

Hey guys help me out. I've got an Anthem AMP-2 that occasionally buzzes, just by itself, not through the speakers. I took a video of it and shot it off to Partsconnexion, who still sells and services Anthem/Sonic Frontiers stuff and they said this:

The noise you are hearing is indicative of a small amount of DC on the power line.
 
The DC is saturating the transformer core and unfortunately the core will heat quicker because of this.
 
You may notice the noise is louder sometimes than at other times.
 
A DC blocker on your AC line may be in order.

Suggestions? My stereo is on a dedicated 20 amp circuit. not sure where the DC could be coming from.

[SunnyDaze]

Does it have a toroidal transformer?

[Shayne]

Yes it does.

[SunnyDaze]

A very small amount of DC into a toroidal transformer can cause saturation. Something as small as a few millivolts could cause your issue.

As far as tracking down the DC source... heh.

This is a VERY helpful resource. Hopefully you can achieve a fix by simply throwing some dielectrics in line.

http://www.diyaudio.com/forums/solid-state/197849-dc-filter-against-humming-toroidals-summary-most-interesting-comments.html

I won't bore you with one of my longer than necessary dissertations (unless requested). Keep me posted, though!

[Shayne]

I've come across that thread in my research but i'm not a DIY'er. None of that means anything to me. I'm looking for a quick and easy fix or a "plug and play" product that will eliminate the problem.

[ataudio]

You need an isolation transformer.  That will block all DC,  plug and play.