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

oldhvymec, I read your 11:01 AM (yesterday) post with interest. I picked up a few portable power conditioners, NIB, made by SOLA, model 63-15-115-6. I was hoping to use them for my home audio system, but the mechanical noise is a no-go, so I'm curious how you quieted your conditioner, and if that would work on these, my model is the SOLA 63-13-115-6................... https://www.ideadigitalcontent.com/files/11375/MCR-Portable.pdf

Thanks.