Pdn,
Check
Equal Loudness Curves to see how volume level affects the presentation of the sound.
Notice that at around 30 db SPL, the average person won't hear anything at all below 80 Hz. At 60 db SPL one begins to hear 30 Hz and at about 75 db SPL the lowest frequencies in the audible range (20 Hz) become barely audible.
This is why bass audibility improves so dramatically at higher levels - put another way this is the reason for the "loudness" button (to help audibilty of bass at low sound levels).
The other important thing to notice on the plot is the area between two different "Phon" curves. It may help to take two extremes, just for illustrative purposes;
1) Imagine you listen at close to 40 Phon peak equal loudness.....then what you hear is contained between the 40 phon curve and the threshold LESS whatever background masking noise you have in the room. Even if you IGNORE the noise floor (usually around 30 db spl) and shaded the ENTIRE area between the curves you get an idea of the signal range that your hearing is working with. ( Anything on the source music that falls below the threshold will fall below audibility - so you are working with a MAXIMUM dynamic range of roughly 40 db SPL)
2) Imagine you turn up the sound to around 100 Phon peak equal loudness contour (yes I said extreme). Do the same exercise and color the area between 100 Phon curve and the threshold of hearing. (Immediately it should be apparent that you are now working with a MAXIMUM dynamic range of roughly 100 db SPL. This is similar to the dynamic range of a 16 bit CD - meaning you will not miss even the lowest level signal on the least significant bit on the CD, provided it is not "masked" by other sounds)
This is the long answer of why you may like to crank it.
The short answer is best explained by Dewey Fin in School of Rock, "Dude, I service society by rocking. Im out there on the front lines liberating people with my music. Rocking aint no walk in the park, lady."