I returned it and bought a Furman Elite15 PFi. The amplifier outlets on the Furman brought the noise in the electricity to 0.0. The other outlets on the Furman added noise to my electricity.
That's interesting. So Furman uses LiFT, linear filtering, which is an active technology to clean up the noise. The problem with EMI gadgets is understanding what frequency they are working at. It's possible that LiFT is increasing noise well above audibility but decreasing it below 20 kHz.
In any event, I think what you discovered is the filtering capabilities of the series mode protection (SMP) built into the Furman which works at about 3kHz and higher.
Personally in bad, apartment complex like environments I could hear it when my Furman was not in the system. Everything sounded more hazy.