Hegel hum?

As the OP I offer thanks to everyone for their suggestions. I’ve never spent this much on a stereo component and was hoping for some assurance that nothing was amiss. From now on I’ll resume my listening position and enjoy the music.

You may try to contact Hegel and explain to their technical support staff this issue..? I would return such amp to manufacturer, if no help etc.. Foot away hum isn’t good, few inches could be okay..

I had many amps, and the only accuphase designs have zero transformer related hum noise. some transformers can be fixed by potting them in qualified epoxy, or putting transformers on shock absorbing spacers.

In fifty years of owning high end audio equipment I have never heard a hum coming from any of my components. 

I've had preamps and amps that were sensitive to DC on the line before.  I've tried many DC blockers and pretty much all of them hurt the dynamics.  The one that I found to work best and not hurt my system dynamics is the Emotiva CMX2 AC Line Filter With DC Offset Eliminator.  It is a great design and does what it needs to do, nothing more.  I have one extra used one with the LED lights not working (a common reported problem) that I could let go for $75 plus shipping if you are interested.  My new Atoll IN200 evo integrated does not hum at all in the same house and location.

My experience with high current Class A or Class AB designs with large power transformers like Krell and Classe is that they normally produce a faint mechanical hum when first turned on as transformer charges and “warms up”.  The hum should not be audible after warmup.  I am not familiar with Hegel in general, but the H400 specs indicate it is a high current design with a large power transformer, so some hum on warm up may be expected.  You state this occurs after warm up. This does not appear to be normal.  I would contact Hegel for recommendations. 

It does not appear you are hearing the hum from your speakers.  If you are not hearing it from your speakers I would not expect it to be  ground loop hum.  If you are hearing it from your speakers, I agree with others to experiment with removing ground loop hum. See the link below that explains ground loop hum and how to attempt to remove it.  If that does not solve the problem, then contact Hegel   

https://www.sct.com.tw/articles/4-effective-approaches-that-eliminate-ground-loop-video-audio-interference