Hegel hum?

If you put your ear a foot from the speakers it is common to hear a faint hiss. But not a hum. This could be a faint ground loop. This would be that the amp is on a different circuit from the rest or one piece of equipment and there is a slight potential. 

To test. Plug everything into a single circuit and see if it remains. 

I should have also mentioned in my first post that the hum is not coming from the speakers. In fact, when I turn the volume up and pause the music, I hear nothing out of the speakers. It's the h400 that has a slight, even tiny hum. When I look behind the amplifier I have a spaghetti plate of wires between speakers, electric plugs, a streamer and a subwoofer but the hums not loud enough to make me try sort that mess out.

The hum is most likely coming from the transformer inside the amp. I use to hear it in my H390. Got a DC blocker and the hum went away. Since grounding the outlet the amp was plugged into I don’t hear any hum. I think what you are hearing is normal. I just purchased a Electrocompaniet intergrated and if I get very close to it, I can faintly her a buzz coming from it. No worry.

My Hegel H590 has a normal, cyclical, mechanical, ever so slight hum.  In over 25 years in high end audio, I've never owned an amp, whether it be tube or SS, that didn't have some kind of a hum.  Some hums extremely slight, and some more noticeable.  With my Hegel H590, the barely noticeable humming sound cycles out after a few minutes.         

Seems most audio systems are enjoyed having your ears equidistant from the speakers, rather that a foot from the amp 😉