Two caveats prior to responding. I really don’t know how clean my power is out of the wall compared to your situation. We just built and moved into our house. So, the power distribution is new. Our neighborhood was farm/ranch land until the last few years. We have a neighbor that raises camels. Secondly, your equipment throws noise back into the power line, so not all noise comes from your house/utilities power distribution.
I made a major change in power to my system, pretty much all in one go. I was floored at the difference, but to quantify the difference is a challenge. The presentation was more detailed, with more air, silence between notes and better imaging. Everything was just more musical. Listening was less tiring.
For me, power upgrades involved adding a Shunyata plug, Everest conditioner and a Sigma power cord to my integrated amplifier. I had a three pack of Venom and some old power cords… so my power upgrade wasn’t really in one step. Later I added Venom NR to my subwoofers and replaced the remaining power cables with Sigma NR. I purchased items with a sixty day return privilege and my salesperson let me just trade up without any loss of funds, even after the sixty days. So, more money spent on power than any other one component. I intend to add a dedicated circuit, but my current power distribution is from a garage on the opposite side of the house. My listening room is over the second garage, so will need a long run to second panel.
I believe that addressing power is the single biggest improvement to my system. Other changes, balanced analog interconnects and speaker cable were more nuanced improvements. Digital cabling (AES/EBU and Ethernet) improvements were the second largest cabling improvement seen on the digital side. Room treatment is probably up there with power as an important component of good musical reproduction.