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.
Surprised at Low Household EMI Readings
I picked up a Trifield EMI100 meter to check for EMI noise around the house. After watching a few YT vids I was expecting some pretty high readings. Surprisingly almost everything was low. The unfiltered outlets where my system is plugged in measure less than 10 milllivolts with all equipment powered on. The worst was the bathroom GFCI outlet at around 65mV. I use a 10-year-old Blue Circle power conditioner, and that output is a few mV less than the wall outlet. The house was built around 1970, and outside of a new fuse box installed a few years ago, everything else is original.
Very happy with these readings as I was considering a power conditioner upgrade. The $150 Trifield meter seems to have saved me a few thousand bucks.