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


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. 
Here are the DC offset measurements using a low pass filter. (DMM probes across capacitor leads)

I used a 1875 watt hair dryer to create the DC offset on the AC mains.

Test # 1
Dedicated Audio room.
Low pass filter plugged into dedicated audio outlet. 120V, 20 amp branch circuit. Branch circuit wire is #10-2 with ground Romex. Length of Romex from wall outlet box to electrical panel is approx 75ft.

Low pass filter plugged into wall duplex outlet. No other loads connected to the outlet.
AC mains voltage at outlet, no load, measures 122.3Vac (DMM, Fluke 87 True RMS)
**EDIT: (I just checked mains unloaded voltage again so I could check for the hair dryer loaded voltage drop. Unloaded mains voltage at the outlet now measured 121.5Vac. Loaded, hair dryer turned on, high heat, low blower, measured 119Vac).

DC offset voltage measured across the low pass filter cap measured 1.6 mVdc, avg reading. (Fluke set on Dc mV scale).
I also used a Radio Shack DMM. Meter set on DC volt auto scale. It also read 1.6 mV avg.

With the hair dryer plugged in, heat on high, blower on low. (This combo setting gave the highest DC measurements).
Fluke measured 0.734Vdc (meter set on auto DC volts. Dc mv meter setting is for 400mV max.)
Radio Shack measured 0.726Vdc.

0.734Vdc (734 mVdc) is more than enough to saturate the core of a moderately sized torid and cause it to buzz loudly. From what I have read 50mVdc will cause a torid to buzz.

Just for the heck of it I ran a few more tests.
Test #2

Low pass filter plugged into same audio dedicated wall outlet.
Hair dryer plugged into a wall convenience outlet in the same room. Branch circuit is separate 20 amp, #12 Romex, for several conv outlets in the room. Approx length of the romex from the wall outlet, the hair dryer is plugged into, to the electrical panel 80 + ft.

Hair dryer turned on. High heat, low blower.
Fluke measured 112.6 mVdc - 113.3 mVdc (Meter set first to DC auto, then moved to mV setting)
Radio shack measured pretty much the same, 112.3 mVdc - 113.6 mVdc.

Here is where, hopefully, Al (almarg) chimes in.
With the hair dryer plugged into the same outlet as the low pass filter the Fluke measured 734 mVdc. With the hair dryer plugged into a different outlet fed from a different branch circuit the Fluke measured 113.3 mVdc.
Just a guess on my part, two things are at play. Both involve the total combined length of the two Romex cable branch circuits, (Approx 75ft + 80ft). One is the inductance of the cable and the other the resistance of the cable. Inductive reactance? One other thought to consider is the utility power transformer. Just going from memory harmonics will travel back on the neutral conductor to the source. Some of the harmonics are dissipated by the secondary winding in the form of heat.
If Al is still following this thread I am sure he will have a better technical answer.

Test #3

Hair dryer plugged into wall outlet in dinning room. Wire is Romex, #12 , 20 amp circuit. Approx length? Just a guess 80ft or so. (Up, down, and all around).
Low pass filter, still plugged into the dedicated audio wall outlet circuit, audio room.

Hair dryer on, high heat, low blower.
Fluke measured 106.7 mVdc.
Radio shack 105.8 mVdc.
Voltage at wall outlet unloaded measured 122.3Vac. With the hair dryer turned on voltage dropped to 116.2Vac.

Test #4

Hair dryer plugged into an outlet directly below the electrical panel.Fluke measured 115.6 mVdc
Radio Shack measured 115.4 mVdc.
Note, here only the audio dedicated 20 amp branch circuit wiring length is at play. Approx 75ft, #10awg wire.
One other thing...... I will have to go back this afternoon, maybe tomorrow morning, and Check for the Line, Leg, (in the electrical panel) that each of the branch circuits are fed from. (For tests 2, 3, and 4). There in, Line 1 or Line 2. I believe that would have some relevance. There’s a 50/50 chance, LOL, some are on the same Line as the audio room dedicated audio outlet circuit that the low pass filter was plugged into for all the tests.