DC Offset Blocker/Killer - where to buy in the USA

   I have McIntosh MC8207, the first unit I bought from an authorized dealer came with a loud buzzing coming from the left transformer, and was replaced with a new unit which came with even a louder buzzing. The buzzing can be heard from 8 feet away. Then I was told to have install new 20 amp outlet that has its own isolated grounding.
   That was done professionally by an electrician who installed two isolated 20 amp outlets, two 20 amp circuit breakers, two copper polls for grounding for each outlet, each outlet has its own neutral and power line. After all this done the buzzing sound was still there.
   I was then told to buy a power conditioner which I did (Audio Quest Niagara) which was like $4000 and that did not help. Called back McIntosh and was told that I might have DC offset in my AC line and was told by McIntosh that I would need a DC Offset Blocker/Killer to which when I asked them where to buy one they told me to go on the internet and search to find one, to which I cannot find one.
  This bothers me a little bit, if you as a company think that I have dc in my ac and i need a dc blocker wouldn't you need to sell one as well. I brought this amp to my friends house and it was the same no improvement, so my guess is that he has dc in the ac line as well.
   So If anyone of you knows where to buy a DC Offset Blocker/killer please let me know, but even if this helps kill the buzzing wouldn't you guys think that this expensive somewhat hifi amp/brand should be silent from the factory. I mean this is two units in a row all purchased brand new.

My house is 5 years old, everything is brand new, the whole neighborhood is about 8-9 years old, my electrician says that I have perfect power coming to the house and everything looks fine.

Thank You



I went through something similar with an amp.  I tried dozens of fixes, from cheater plugs, extension cords, turning off all the breakers, different outlets, inexpensive filters, expensive filters, ground loop eliminators, DC blockser, power conditioners, power regenerators, isolation transformers, you name it.  Nothing worked.  Ultimately, sometimes it comes down to the electricity coming into your house and how it interacts with the component.  I hope you have an experienced electrician, because most don't measure/don't know how to measure/don't believe are important, the kind of things, to vanishing small levels, that can be causing the problem.  And if he does identify it, good luck getting your local electricity company to address it.

I'm also here to tell you that if you buy a similar priced amp from a different company, there's every likelihood that it won't hum.

As much as we like solving a problem once it's been identified, sometimes the expedient thing is the best route (i.e. I hope you haven't exhausted the store's return/refund policy).


It could be the electricity coming to the house form the outside, I've done everything I was told to do and more and nothing helped. The only thing left to do is convincing the electricity company to come out and maybe put a power analyzer on the entrance meter and record if there are any anomalies. 

The store has been pretty good with me as far as exchanges and getting new units to me but even I told them that I do not want them to get me new units but find a solution to the problem I am having,  it just that they should've know more about the product they are selling or they should have been trained from McIntosh of how to address this kind of problems. 
I wonder if one of our resident Audio Guru's could build a Heavy Duty DIY Noise Blocker and charge you accordingly?  I'm talking something better than the Emotiva which uses a circuit board?  I would think point to point wiring would be the way to go.

I would be all in to have something made by the Audio Gurus if price is right and if product performs better than the Emotiva 
I think you have done everything you possibly could have to resolve the problem. I'm glad the dealer is refunding your money, but I think they should have been more active in resolving the issue. Especially having you install wiring, though a good thing in the end, should not have been something you had to do.
Hopefully, you can find another amp to your liking.