Listening comes naturally, doesn't it? Well sure, everyone with normal hearing can listen, but what do they hear? What I'm talking about is listening as a focused activity--as opposed listening where music serves as background to something else, reading, driving, running, working, or washing the dishes--active listening can be a lot more rewarding. You hear stuff in your favorite music, maybe rhythm guitar patterns, overdubbed vocals, or instruments you never knew were there can suddenly jump out of the mix. It's stuff the band may have put a huge effort into perfecting, that you only notice when you're really listening.
Bass drums and bass guitars can easily get lost when you're distracted, but they provide the very foundation of dance music and rock & roll. Paul McCartney's bass playing with the Beatles was amazing, and if you're really listening you'll hear every note. On acoustic jazz recordings you should be able to hear every pluck and slide.
Stereo imaging--the placement of instruments and vocals from left to right can be fascinating. Imaging is especially cool over headphones where it's all in your head. With speakers you can sometimes hear a sense of "space" surrounding each instrument. There might be spatial depth so some instruments sound like they're in front of other instruments. Over really good speakers you can almost "see" the musicians in front of the speakers.
The word "transparent" plays a key role in the audiophile lexicon and refers to the ability of components and speakers to disappear so you feel like you're hearing the original sound of the recording session. Of course, that's not literally true--transparency is a matter of degree. When everything's just right the heightened clarity lets you feel like you're getting closer to the true sound, and well, you feel closer to the music.
Just listening for these qualities will make you a better, more aware listener. One thing's for sure, the more you listen, the more you'll hear. And most importantly, you'll get more out of the music.