@hilde45 I’m going to make an assumption you are an experienced listener, your components, speakers and room are on the level to resolve changes in components or cables.
So in my experience…
1. Interconnects
2. Speaker cables (super close second to ICs)
3. Power cables
4. Digital cables
5. Ethernet cables
As to the component to start with on a power cord upgrade? I’d say amplifier first, then power conditioner for your sources, then sources(turntable being very last and I would just use a good stock cord).