Oh, yes it was! The mind will tend to discern the louder of two signals as the "better." The difference can be as small as .5 db, perhaps less. That is why level matching to at least .1 db is critical.

I am not surprised that you were unable to discern the problem with pop music. Tell me, what does an electric guitar sound like? You know one when you hear it, but is its sound being properly reproduced by the recording and system? Given that the performer has limitless settings on the instrument, the recording is being made with a gazillon tracks, mixed, reverbed, echo, compressed, and otherwise beaten to a pulp, how can you possibly know if the reproducion is accurate? Given the compression used on almost all pop material, the recording likely required all 16 bits almost continously unlike the classical recording that (hopefully) was not compressed and had actual dynamic range. Then, there is the matter of comparing reality to virtual reality. I know what Ray Still's oboe or Adolph Herseth's trumpet sounded like in 1960's Orchestra Hall in Chicago because I heard them so often. I have no idea of the inherent sound of a synthesizer because no such standard exists. Indeed, distortion is often deliberately introduced into pop music.