How do you learn different frequencies? I've read where people say they "hear a dip in the 8k range".
I'd love to be able to fully. understand people's reviews, as well as write my own one day.
As a not too experienced Head-Fi.er my feedback is mostly on the musiclistening.
If you have to ability, try to pick up and play a guitar, or bass or any other instrument of choice you probably should, I think that me just learning the basics of electric and aucustic guitar made me enjoy my music a lot more. It's a bit hard to explain, you just become more aware of the instruments and therefore you enjoy it a lot more.
And trust me, you don't have to become good at it. I could probably qualify for the worst player in the world, during the 5 years I've had my guitar I doubt there has come out a single clean tone :)
Onwards to the actual listening, a lot of more mainstream "rock" genres the drums tend to take the role of just setting the rythm. This is a trap I fell into. Beginning to listening to more and more progressive music (well, this was somewhere around 5 years ago, when I picked up my guitar) I realised that especially drums has so much more to give than just being a backgrund rythm. About the same argument can be made with the bass guitar. Focusing on those parts in the songs altered my whole listening experience, and made me really engage in all of the noices coming out of my speakers/headphones. Not only the guitar and vocals which I primaraly focused on before.
What I would like to say with that is that is, try to sit down and listen to the drums or base, or any other of the more discrete instruments (Would heavily like to recommend Dave Matthews Band or Porcupine Tree for the drums) and you will probably see music with new eyes coming out of it.
Finally, I have also kind of realised that taste in music is a thing that develops over time, as you develop as a person. I don't think you can or indeed should try to change your music habits too much. It's a matter of being yourself and forcing stuff you don't want to listen to down your own throat because you want to be someone else is not a good way to go about it. (well, this sounded a bit patronising, and maybe not a discussion for this forum, but anyway) :)
Also focus on the imaging and positional cues. Generally, at some point, spending more money improves on this more than on other aspects, but of course, it depends on other factors. Headphones of course have a very small soundstage compared to speakers, although when you make the jump from the HD600 to the HD800 for example the improvement isn't all in size but the precision of the instrument placement. Whether or not it's worth another $1,000 depends on the buyer - personally I'm not giving up steak dinners saving up for the HD800, but hey, in a few years if I can get a used HD800 for $600, I'm gonna get that instead of whatever replaces the HD650 by that point.
Also even if you do have speakers, sometimes it's the room they're in that is restricting proper imaging because you are getting too many unwanted reflections (it also screws up the frequency reponse). Then it's also how the music is recorded - was it recorded properly? Or are there enough instruments in it so even if it isn't necessarily an acoustic audiophile recording, you can still have a sensible soundstage as per a live performance? Also don't look for depth where there is none - generally only audiophile recordings have proper depth. In most recordings that are otherwise well recorded, the drums won't be that much farther back, but they should still be so unless you're using speakers or headphones that have a very forward presentation (even if so, the L-R panning must be consistent).
It just comes with time. You have to listen to the music you love, then try to figure out why it sounds good to you. When you hear something that make you go "wow!", pause for a second to think about what that was.
But really, it just takes time and listening to different gear. No need to rush it or do any particular exercises.
And for the record, half the skill - or more - in listening is trying to decide whether you really ARE hearing a difference or if you brain is playing tricks on you. That is a skill that seems to be in short supply in the high-end audio industry.