Puzzled...

Just say, you have noticed a difference in SPL (sound pressure levels) between different albums/tracks when the volume level of your preamp is at the same gain setting, sometimes very large SPL differences. This is consistent and repeatable.

Then, say you notice that many times, by and large, more often than not, etc., that you perceive that the sound quality of titles with a higher recording level (requiring a much lower gain setting on the preamp for a given SPL) tend to sound significantly less enjoyable to you than those that require higher volume level settings on the preamp for the exact same SPL.

Next, you realize that the poorer sounding titles require volume settings significantly below the preamp manufacturer’s specified "Unity Gain" setting level and the better sounding recordings require settings at or above that Unity Gain setting for the same SPL.

Why?

Remember, you set SPL levels for all titles the same and your observations are not always true for every title, just much of the time, yet consistent and repeatable for a given title.