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

But one thing you mentioned would really help. If I shut off everything in my house.. except the line to my audio system.. would that be comparable to getting a dedicated line? 

I get what your all saying.. makes sense.. and not sure if im coming off nutty but i am pretty relaxed.. just wanted to play around with some measurements.. especially to see how well these PC, conditioners, etc are working.. Thinking of putting a dedicated line in.. aside from ears.. but just wanted to play around with the idea.. so if i shut off everything.. except breaker line to audio system.. that would get the same results as a dedicated line?

For one.. I never tested anything to see what the condition on my circuitry is.. My neighborhood lucky enough doesnt have any smart meters yet... i know smart meters can go a long distance. But the point is.. if I can test my home... then maybe I can see what is causing my lines to get.. dirty or whatever.. or measure in my house what devices are giving off the most interference, etc.. not sure why finding a cheap meter to get an idea is such a big deal. At the moment im using a Shunyata Hydra 6 conditioner, and a mixture of Shunyata and Silnote Power cords, and a ADD-POWR SYMPHONY PRO EMF Conditioner. They all have made a difference in each step.