aladdin,
You can check out the
Etymotic Research website to learn about their ER4P and ER4S, and also their musician's earplugs. You can buy their products directly, but they're a little more expensive than going through a retailer such as
HeadRoom
The ER4P is designed for low-power portable CD and MP3 players. The ER4S model is designed for use with powered amps and home stereo systems. In the past you would have to buy both models if you wanted great sound using portables and hi-fi systems. But they now sell a small adapter cord that turns the ER4P into the ER4S. So if you buy the ER4P model with the adapter, you will have both models of the earphones at a cheaper price!
Etymotic also makes a cheaper model of their earphones, the ER6. I do not recommend these at all... I don't think they sound good enough to be worth the $150.00 price tag. For that money, you're better off saving for their ER4 models

The ER4 earphones come in a plastic box which holds all the spare eartips and other things, and you get a small pouch that you can roll up the earphones and put it in. I always just store the phones in the small pouch, and carry it around in my pocket with my MP3 player. In my laptop bag I have one of those hard plastic eyeglass cases and use that to store my Echo Indigo soundcard and the Etymotic ER4P adapter cord.
The Etymotics themselves take some getting used to, and you have to practice putting it into your ear. It's easy enough to do, but if you don't push it in far enough, you don't have a good seal and you'll be able to hear outside noises. And you'll also have poor bass response. But once you get it right, you'll be in total silence. Being a DJ, you no doubt have some sort of permanent ringing in your ears (as all of us music fanatics do!) so of course, with a good seal, you'll hear the ringing pretty loud, along with your breathing, and you can hear yourself talk, which is odd.
But you get used to all this in no time and it's no bother.
Using the Etymotic earphones, it's like you're in a private, quiet studio and you'll become oblivious to everything around you. First-time Etymotic users often get what is called "Disassociative Disorder" which is where you feel detached from the outside world. It's quite an experience to be listening to your portable music while walking down the street, and you only hear the music - and it sounds like you're listening at home on your hi-fi system! You feel like you're watching a music video. And sometimes it's hard to take off the Etymotics, because you don't want to go back to reality. For me this phase lasted a good... 3 or 4 months. Now I'm pretty used to it and it's neat to watch others go through the phase

One big plus (or big minus, depending on your situation) is that people will barely notice you have the Etymotics on. With regular big headphones on, everyone knows you're doing something with audio. With the Etymotics, it's pretty common to look up from your laptop and see someone talking to you and they think you've been listening to them the whole time

I swear the audio is top-notch... for DJ'ing I doubt you'll have much use for it. But for working on studio projects, it's great!
One inexpensive way to test out if you'll find the Etymotics comfortable is to buy the Etymotic ER-20 earplugs. They cost about $10 and the tips are exactly like the ER4 tips. So you can experiment with the earplugs (you stick them in your ear the same way) and you'll know if you want to try out the earphones. HeadRoom also has some sort of 30-day money-back guarantee on their headphones, so you can contact them about the details if you ever do decide on trying out the earphones.
Sorry if I typed too much here. I'm a big fan of the Eymotics

There are some drawbacks to using them (same drawbacks also on the Sennheiser HD600) so if you or anyone else reading this wants more info on these, let me know and I'll go into more detail.
Don't forget to check out the Etymotic and HeadRoom links above. Even if you're not really interested in expensive headphones, these sites are very informative and in no time you'll be up-to-date on all the good headphones, and know a little about how to protect your hearing
