Surprised at Low Household EMI Readings

@sns funny guy. good to know when condescension is called for, you’re the go-to.

jaybe

... What other nasties live might live in my power and how can they be detected? ...

You could argue that any deviation from a perfect 120VAC 60 Hz sinewave is "dirty" power. You could observe that on an o-scope.

One of the first things I learned when I started pursuing high end audio was to listen first and... well, over time was to ignore most measurements. There are so many variables that to isolate a couple and attribute the results to them will be too confounding to be helpful. I was trained and professionally a scientist for a decade. 

If you want to put together a great sounding system then looking for measurements and applying logic, then making purchases is dead end. You will end up with a very mundane uninspiring sounding system. Listen to well seasoned audiophiles and use observation as you primary tool. 

I second the comment of the other member asking about the correlation between EMI and dirty/noisy AC. I thought EMI was generally caused by source cables being too close to power cables which interfere with the source cables via electro magnetic "induction" whereas dirty AC is either coming in from the utility company that way or there are appliances/components in the house that are (often having a motor of some sort, or, in my case a Keurig coffee machine) pushing DC or some other signal back into the line that is then being presented as a hum in the audio system. My home has a steady low level hum in the AC that regardless of which circuit I use, can be heard on most audio systems I have around the home. It must be coming in from the utility or there's one appliance plugged in somewhere thats polluting the entire electrical system.