In 1969, a Canadian educator, Laurence J. Peter, presented to the world the Peter Principle. People and systems in a hierarchical structure are continually elevated (or upgraded) until they reach a point of incompetence, and there they stay.
This now-famous principle was based on a lot of research, personal observations, and not a little bit of satire. Smiles and guffaws aside, the reason it became so well know is its basis in truth. We've all known someone that's exemplified Dr. Peter's principle.
We can apply his principle to our stereo systems. We build, tweak, polish, update, and rearrange until audio nirvana has been attained, and then we do it all over again hoping to reach yet a higher level. Eventually, we reach a point where wheels spin without forward motion.
We've Petered out (to pun a phrase).
In my experience, this happens more when we're tweaking rather than addressing basics. A better cable, power supply, isolator, or vibration smoother can improve sonics but only if it's helping a deserving performer—one that has been properly vetted for the job.
Take a 50,000-foot view of the system before delving into the minutiae.
