1. The first step above "pure junk" is for more "bass and power"; with most people never "growing" any further.
2. Next comes a taste for superior midrange and high frequencies, but without losing the "bass and power". It is here that "Audiophiles are born". However, most audiophiles stop evolving at this point; being reluctant to take their main focus from "bass and power", and consequently only search for further enhancements. The most expensive and complex components are those "enhancements."
Still, the basics and fundamentals of music reproduction have now been accomplished at this stage, which means the system can now be accurately described as "High-Fidelity". This is the single most important milestone on "the journey".
3. The next step is much more difficult; replacing the past focus on "bass and power", and/or "convenience", for midrange naturalness and low-level information. This "area" is where the vast majority of musical information resides, and it's also where analog software and tube electronics excel.
It is not a mysterious coincidence that those audiophiles who end up preferring tube electronics very rarely go back to solid-state. It is also at this stage that audiophiles will make a final preference for analog over digital.
4. Finally, some of those left may decide to go to radical and extreme lengths to maximize the retrieval of low-level information and minimize the system's inherent, unnatural qualities.
