How To Do You Measure the Quality of Your AC Power?


What is the best way to measure the quality of the AC power feeding your listening room? Is there a device you can plug into an outlet that will give you the voltage, frequency, the total amount of distortion relative to a perfect sine wave, etc.? Furthermore, how would you measure the ability of your AC main to deliver transient currents?
It seems like there may be a scenario where you could measure your power quality to be excellent but somewhere in the line you could have a loose or poorly made wiring connection which under heavy load (such as powerful bass notes) you could run into trouble with power delivery. In this scenario, an AC regenerator would not help you, or would help very little.

Just curious what methods people have come up with to systematically analyze their power and how they use those measurements to drive buying decisions or repair work, if needed.

Edit: My apologies for the title typo.
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Showing 1 response by audioquest4life

I use PS Audio products which can measure the amount of incoming THD which is usually in the 3% plus range for me. After regeneration, the THD drops to the -0% range. I feel that that method of measurement and subsequent cleaning of power is beneficial to the overall sound quality. 
Additionally, I have installed Environmental Potentials EP-2050 power line industrial EMI/RFI/spike filter. These are used in massive server farms, IT systems, medical electrical systems, large corporations where critical systems rely on flatline clean power delivery. 

On cables, especially newer Shunyata with DCT to help with noise, hmmm, they are able to lower noise floors below the already impressive -0% noise floor. Can we even hear that? I mean really, can we hear that level of noise reduction or is it already below the perceptible hearing level that would make a difference. What  does a .0001 noise floor sound compared to a .001 noise floor? Can you hear it? Power cables are part of recipes…many in the community hear differences in what power cables do, myself included. Heck, my stock cables sound different, and better in some positions in my system than other power cables. Ahhh, different….what’s that? Noise floor, hmmm. Did that new cable lower the noise floor and I heard it, or, did it change the perceptible audio spectrum which alludes to more recessed mids, increased bass, and sizzling higher frequencies. Look, power cables are like ingredients in a recipe. They can alter the soundscape, but, be careful what you ask for. Power delivery by any cable to your system by default is going to be great. When changing out power cables, all you are doing is changing the ingredients in the power delivery chain which may or may not change the flavor of your sound. Trust me, I just splurged on a half dozen Shunyata Sigma NR 2s and experimented with different power configurations and each component reacts differently to power cables, sometimes to the detriment of sound quality. Get your ingredients right and in the right order. Another example of new Sigma NR2s in my system…my volume must be turned up at least 1/4” higher to get the same loudness level as before. So much for instantaneous power delivery of cables. My system already jumps out at you with instant speed and can play loud as heck…but, power cables alter something, maybe the background is quieter, but why? Ahhh, my highs are slightly veiled and lost some organic sound qualities. Switch the ingredients, maybe new cable break in. Another cable ingredient to consider. 
 I agree with other posters about your electronics and amps having the ability to cope with power anomalies to a certain degree which still results in awesome musical enjoyment. 
Methodically evaluate what you do and do it in small steps. Sometimes, the little things are the biggest payback in musical enjoyment.