Well I finally have reached the point that I'm very happy with every piece of equipment in my system. The last little bit was some tube rolling in the DAC, to get that synergy between it and a new network transport.
So what's left EMI? It does exist, and it's measurable. Does it matter? I guess there's no way to know unless you remove it.
Power conditioners, This Could be the least data-driven category in all of audio. No real compatible data, Just lipstick and perfume. So I changed my search to " Scientific equipment EMI filter". What I found was a collection of filters with specs.
This one looked like a good candidate. Any thoughts?
Plug-and-play CleanSweep AC Power Line EMI filters reduce electromagnetic interference where it matters - in your application. CleanSweep EMI filters offer superior EMI attenuation than regular filters, providing noise reduction in both differential and common modes, and, uniquely, in ground.
www.onfilter.com
EMI, Electro-Magnetic Interference, isn’t measurable on a wire / power line, it is by definition electromagnetic which is measured by an antenna. It can influence wires (as antennas), but unless it is a VERY STRONG electromagnetic emission (such as near large electric motors, power-lines with nasty dirty loads/power, etc.) it will not have a significant influence on a device (eg: audio equipment) that runs on DC from an internally regulated, filtered, rectified power supply including a transformer, unless the equipment is truly a dismal piece of garbage or has serious filter capacitor problems (or you live inside a power-plant). It also would need to be at or at least near the audio range to be significant, even after the power supply. Rest assured, unless you’re buying a really cheap POS the Engineers have designed the power supply to filter out noise at any normal level.
The FCC regulates EMI & EME. A device, whether it’s a wall-wart, an inverter or radar devices (which my company makes), … it can not emit electromagnetic energy sufficient to cause interference in nearby devices. Further, to comply with the FCC these devices must be able to reject a reasonable amount of electromagnetic interference without it affecting its performance. Your amplifier, tuner, preamp, streamer, … also are designed to A) not emit high levels of electromagnetic energy, and B) operate normally with a normal level of electromagnetic energy.
So you live under HV power lines and run a high-HP motor in your audio room with a dirty modified-sine-wave inverter powering your equipment? Buy a quality ferroresonant power conditioner, and build a faraday-cage around your audio equipment, your only real hope.
Any device that is advertised to reduce or eliminate EMI by filtering your power on your outlets is pure bunk by definition of what EMI is. At best it can filter surges and noise on the power line, which is not EMI. But again, if your equipment is well built it already does that to a degree that 99.9% of people plugged into normal grid power will need, 99.9% of their day. There are exceptions but it is not common.
So how does a meter plugged into a power line determine that noise on the line is produced by EMI? It can’t. It is probably merely measuring/indicating any deviation from a perfect sine-wave of 120VAC RMS (which is 340V p-p) and inflating it by using a peak-peak display of that voltage. Use an RMS calculation
https://www.allaboutcircuits.com/tools/rms-voltage-calculator/ to determine what that AC voltage really is, compare it to the 120V RMS line and realize that this is exactly what your equipment’s power supply is designed to filter. Unless you’re one of those .1% people who actually need it (or just enjoy buying additional gear) it is redundant.
