I bet there is an astounding percentage of hermit Agoners. Wow. To the OP, Speakers and source components first. But reality is, that is a MASSIVE variable with all number of possibilities. No easy answer. Power has to be second. If power sucks, so does everything else. Speaker cables next, then on down the line. And I too disagree that the entire loom much match, plenty of people making great music with a variety of cables.
What makes the biggest difference in sound quality?
When making changes or adding things to your system, what makes the bigger difference in sound quality on preamp‘s and power amps? Interconnects, speaker cables, power cords, or fuses?