What could be causing this spike at 60Hz?

[FargateOne]

I have a 2010 Asus laptop and a miniDSP Umik-1 since 2015. All worked well with REW and Dirac 3.0 for my thousands of measurements done since then. Yesterday, during the night so in a completly silence environment ( during the day Dirac mic level reads -48issh dB but last night in a more silence room mic level was -41dB) this 60Hz appeared every where. It is NOT a Hummm. My Arcam AVR-21 is dead silent even if I push the main volume at 90 (usually 55-62). With one point measurement only the spike is in all channel but surround left and sub right. In a 9 point measurement withthe help of the propagation window, the spike is in all channels.
I know I can check with REW (need to find a moment for now)but in the mean time what is a probable cause? usb cable? mic itself? Dirac software? or worst of all my receiver?
Fronts

Center

Surrounds

Subs

 

[Todd Anderson]

That's weird. And you're sure your UMIK-1 microphone was selected as the input source, and not the laptop mic?

I would definitely do RTA with Room EQ Wiz.... see if that spike is still there.

Was something in your home running? A dishwasher? A Dryer?

 

[FargateOne]

That's weird. And you're sure your UMIK-1 microphone was selected as the input source, and not the laptop mic?

I would definitely do RTA with Room EQ Wiz.... see if that spike is still there.

Was something in your home running? A dishwasher? A Dryer?

As usual I put all 60Hz sources to off, the to off, the clim and the heating of the house to off.No neon light. And that night it was past midnight. RTA confirm the spile at 60Hz to any channel choosed. I took my son's laptop and RTA showed the same spikes. It makes no sense that it would be the cable remains the Umik-1 isn't it?