Just noticed this.
Bit late and not really an answer to your question.
I have a McIntosch MA7000 and a PS Audio P10? Both have a slight hum audible from 1 meter away. Without the P10 the hum of the MA7000 can be heard at the listening position.
I tried the PSM156 and the hum was horrible. Same as without the P10.
I should give the Audiolab DC block a try!
Sorry for being blunt and coming across condescending, but instead of applying half working band aids for insufficiently designed kit, Iād look for something more competently designed for the job.
I canāt believe the ignorance of some players in the high end audio industry!
Hey Marin, I do not disagree!
My only problem with that is that the same equipment will act differently in each household. The electricity in each house is different with different appliances impacting the grid.
I have spent a lot of time the last 10 years cleaning up and improving our electricity grid. Even had the main board completely changed.
Getting competently designed kit is only part of the story and easily achievable. Moving to another house is a bit harder 
Power problems seem more prevalent in the US, perhaps EU gear isnāt especially designed to deal with large dc offsets and voltage fluctuations?
McIntosch and PS Audio are both US brands ā¦ many user report hum problems across globe ā¦ and many users state their units are completely silent ā¦ go figure ā¦ I think there are so many factors at play inside and outside the audio equipment that each and every situation is different ā¦ some are never resolved ā¦
And they both sell power conditioners, whereas Hegel doesnāt 
I have a DC offset issue in my home. The source of the problem is outside the house, so I added a DC blocker from ATL Audio. I had intended building one myself, but the cost of components etc. ruled out this approach when I could have a quality product delivered for ā¬90.
Before buying ā and I would recommend the ATL with descrete diodes ā do some checks, and turn off all electrical equipment one-by-one, especially fridge freezers, to see if the source is in your home. Also, be sure itās torroidal hum you can hear.
Thatās actually, why there are regulations (slightly different for each country) for electric installations and electronic devices to be operated while connected to such.
Those mandate faultless operational conditions for intended use within predefined maximum acceptable EMI conditions (including DC offset) to avoid such reported misbehavior.
I do know for fact, that not all businesses follow stringent testing during and after the design phase, just to meet schedules and budgets set by technically agnostic management, but rather just sign conformity paperwork with hope to get by.
Itās a shame, really!
The problem with toroids, and itās not a design fault itās an inherent property, is that even a minor DC offset can saturate the core leading to mechanical hum.
DC blockers remove the offset and kill the hum.
I had some further thoughts around a few of the earlier posts.
The blocking capacitors have to be large enough to present a sufficiently low impedance at 50/60 Hz to enable the PSU filter capacitors to charge quickly from the rectified, transformed AC. If the DC blocker isnāt rated for an amplifierās operating current, a possible symptom could be lack of bass. Thereās a lot of energy in bass, and a high impedance DC blocker would restrict the charge rate of the filter caps, possibly leading to power rail sag and a lack of bass output. It would also result in a significant increase in distortion.