Whats a good economical way to test the electricity on a circuit?


Whats a good economical way to test the electricity on a circuit (like noise, dirtiness, etc)? Any suggested meters or analyzers? Want to see where my circuitry needs work/cleaning up.
deanshias
Hasn't heard Michael Fremer say ONE dedicated line, and then explain how audiophiles used to believe you needed more, "which is a really stupid idea" (his words not mine!).  

Like I said, its not that you can't measure the noise, its that its a waste of time. Because the noise is there. Guaranteed. And so being as we all are limited in our time and money it does no good - no good at all - to spend time and money only to confirm what we already know: there is indeed noise!  

People can prove this in like ten minutes. Already explained exactly how to do it. How many have bothered to try? Zero. Yet here we are reading all their uninformed opinions. 

What someone should do, maybe I will, cut and paste all the same old posts so next time someone asks the same question we can provide all the wrong answers in one fell swoop. 

Please someone go flip the breakers. There's only like a dozen people I have done this demo for, most of them absolutely convinced it was BS, half of them not even audiophiles, every single one shocked at how obvious a difference it was. One guy his wife, I said What's your favorite song and played it for her, then excuse me a minute went and flipped the breakers came back do you mind if we play it again? Instant it was done she is all excited says What did you do it sounded SO MUCH BETTER!!! 

Yet here we are whole slew of audiophiles supposedly willing to do anything to get better sound yet too lazy to try this one simple trick. But all with time to post misleading opinions. Sad.
https://ultimist.com/video/2018/07/21/michael-fremers-listening-room/
Skip to 15:50. Please.
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Get a decent DC filter , or if you have a couple of $$$$ get a conditioner.. 
I didn't believe i had bad current until my brother came by with his newly purchased ifi or isotech ( don't remember) might have been powerstation .. the rest is history 
I looked into measuring "noise" on my AC mains, and the least expensive approach would be about $800 to purchase the necessary equipment - and I was unsure if I would be able to actually do it accurately and more importantly, safely.

I would need something like this, in addition to some high-current probes, and oscilloscope, and a filter.

FWIW, I was looking at a device called the SineTamer, which is primarily used in commercial, industrial, scientific industries. Looks interesting and I still might give it a try some day.