It is a personal experience. However, if we call "zero" the level where there is some loud music coming out of the speakers and "hundred" the live, unamplified symphony orchestra or chamber group then we have a lot of dynamic range to assign percentages.
However, I'm not that subtle myself. I can only distinguish binary (e.g "night and day") between listening for the umpteenth time to a program that I already know by heart (night), and hearing it again in a better way (well... "day"). Yes, after many enjoyable additional listens post-upgrade, the previous "day" might slowly turn into dusk... and that's when the itch needs scratching again.
However, I'm not that subtle myself. I can only distinguish binary (e.g "night and day") between listening for the umpteenth time to a program that I already know by heart (night), and hearing it again in a better way (well... "day"). Yes, after many enjoyable additional listens post-upgrade, the previous "day" might slowly turn into dusk... and that's when the itch needs scratching again.