I have been pursuing the high end for fifty years. Tweaks are critical in getting the most out of an audio system… period, no question. I go through a component upgrade, then upgrade / choose interconnects, then power cords, and isolation. Then I enjoy the system for seven years or so. Then, upgrade again.
Each of these steps provide greater performance. Each disproportionally improves the sound quality.
One of the great reviewers from The Absolute Sound once said something to the effect that he had heard good sound systems but never a truly great sound system without all the tweaks… cable elevators, carefully chosen interconnects, power cords, isolation devices. My experience as well. You want great sound you have to put in the effort to achieve it.