Power cables first, and as others have said that will reveal other deficiencies. ...And so it goes. Any effective change will be a revelation, and the next step is a function of what you upgrade first.
After upgrading power cables, my next step was an oversized PS Audio PowerPlant. That made an even more substantial difference. (I already had "good" interconnects, so those got upgraded to very good ones after everything else and now I am done for the time being...)
After upgrading power cables, my next step was an oversized PS Audio PowerPlant. That made an even more substantial difference. (I already had "good" interconnects, so those got upgraded to very good ones after everything else and now I am done for the time being...)