I know everybody is different but to this day best improvement I’ve experienced was adding a power conditioner. I added a Pass Seymour outlet and was a little taken back with what I heard so decided to try a Running Springs Hayley almost 20 years ago.
Noise floor went black from what it was. Every musician in the sound stage had there own space/air around them. I had never heard anything like that, with every move up the Running Springs line was an improvement.
Maybe everyone’s system reacts different but I have always used a passive conditioner since the day I put the Running Springs in my system. Power cables are also as important in my room. They all have there own flavor which makes things fun. Don’t even get me talking about high end outlets.