Keeping up on the audio literature I realize that some people have power that does not need conditioning. I have never been one of those. I now have two direct lines for my system, one for my amp and one for my power conditioner which powers the rest of my equipment. Each of these has made a significant improvement in sound. So I occasionally try my system without a power conditioner (when I make a change). Last time was a few months ago… I put in a Cardas power strip and took out my Cinepro Power conditioner (75 lbs… although 20 years old,was very highly rated). That test lasted less than a minute. The sound became flatter with a much higher noise floor. Over the years the SQ for me has always been wat better with power conditioning.
High power cords make a huge difference. That is the reason there is such a huge aftermarket. If you want a really great sounding system, well chosen high end power cords are required… just like interconnects and cables.