A note about terminology:

Sound—like light—is a wave, and the spectrum of sounds (which corresponds to a spectrum to colors) ranges from low to high. The closer together the waves are, the higher the sound, and vice versa, so that "low end" and "high end" describe the bass-heavy and trebly side of the spectrum, respectively, with "midrange" frequencies in the middle. In broad terms, "bass-heavy" music that relies heavily on low frequencies, like hip-hop, does better with headphones geared toward the low end of the spectrum. Pop music tends more toward the treble. And good midrange reproduction is what you want when listening to jazz, classical music, or well-produced rock 'n' roll (i.e., to "good" music).