Unknown electrical complication affecting my audio system

[Roland68]

The amp is like 50kg, but the DAC & pre were fully inspected in the factory( normal environment) no sign of humming. Probably I will take one component and check somewhere.

This started after hearing humm in the whole living room even do when everything was disconnected, an hour later I heard movement in my neighbor apartment, right after the humming in the room stop.



Here in Germany a normal electric company doesn't have sophisticated equipment to do this measurements. Companies at this level for private homes are quite expensive.

But we're talking about a hum that doesn't come from the speakers, but from one of the devices?

 

[solderdude]

The amp is like 50kg, but the DAC & pre were fully inspected in the factory( normal environment) no sign of humming. Probably I will take one component and check somewhere.

This started after hearing humm in the whole living room even do when everything was disconnected, an hour later I heard movement in my neighbor apartment, right after the humming in the room stop.

It is quite possible your neighbor was using some device that made a lot of (contact) noise (hum from a motor or pump etc).
After it went away you may be more triggered by hum and started to notice your amp was humming a bit while it always might have done that but at such a low level it didn't bother you and then found out other devices also hum a little.

Here in Germany a normal electric company doesn't have sophisticated equipment to do this measurements. Companies at this level for private homes are quite expensive.

HF noise will not create audible hum. DC also isn't the problem as you tried that.

It is my suspicion that you being annoyed by the hum from the neighbor triggered your ear and started listening for this.

You mentioned other devices also had an audible hum... take that to someone else and listen over there.
I suspect that the device will hum just as loud over there than at your home.