Summary

Exceptional sound. Excellent isolation. Customizable fit. Blah, blah, blah - read the reviews these are the best in-ear canal phones out there. People love them. Also, the company stands behind this product. My 3 year old ER-4s broke a transducer. I sent them to Etymotic with a nice note - hoping they could fix them for less than the cost of a new pair. Ten days later I got them back - they replaced both transducers, free of charge.

Strength

Sound - clear, accurate, full
But you will realize that you need to boost your sample rate on imported music files to take full advantage of these phones. So you use up your hard drive faster - its the price of quality. Of course, iTunes downloads will comparatively sound like crap.

Weakness

Stethascope effect when the wires rub. Handy shirt clip helps to isolate the wires.

Customer Service:

Great - read above.

Summary

I use isolation phones for stationary listening (usually sitting). When on the move, I prefer open air phones so all the concern about microphone effect is irrelevant to me. I wouldn't recommend isolation phones for walking or running anyway, it can be dangerous. I listen to all kinds of music and am also a musician.

I've been using the ER-6's for a few years now and love them. They finally failed (hot car I think) so I decided to upgrade to the 4P's. These phones have better audio quality than the ER-6's and are more durable as well. The triple flanged tips seem to be less comfortable that the ER6's since I seem to have to shove them further in to get a good seal. Once sealed though they offer awesome isolation. I may start using them with the foam tips to alleviate the discomfort. Etymotic should provide at least one pair of each sized foam tip so that the user can determine which size is best for their particular ear physiology.

Excellent product. The most common complaints I have seen seem to be the microphone effect and lack of bass. I noticed a small effect then turing my head. By using the clip high enough up to put a lot of slack in the chord this we eliminated. As far as bass response is concerned, I must not be a bass junky because it sounds excellent to me.

Strength

Excellent audio performance. Awesome isolation. Both better than anything I have used before. Durable construction. Very portable.

Weakness

Triple flangs tips are a bit uncomfortable when inserted enough to produce a proper seal. Etymotic should provide a pair of each foam tip size.

Microphone effect is not a weakness but a characteristic of in ear phones. If you want to move around while listening, isolation phones in general are not for you.

Summary

Great product, especially for travellers. Isolation is great (better than most active noise cancellers) and they are super portable...but don't miss your flight announcement when wearing them! Better, more expensive in-ear phones are available though. Not for everyone - experience depends on fit. Try http://www.sensaphonics.com/prod_ety_sleeve.html to get custom fitted ear pieces, which will GREATLY increase comfort and bass quality due to greater seal.

When I first got these phonez, I was amazed at how much better they sounded than Bose noise cancellers and 99% of ear-buds. Much closer to Grado RS-2 and Sennheisser HD-650's I use as a reference. You can hear the difference between MP3 and lossless coding with these, and bass benefits from using external phone amp w/ iPod. .

However, bass is still a weak point. It's there, but has no impact, little texture, and is disconnected with the music sometimes. What I mean is that a bass guitar doesn't always sound like it is playing in perfect time w/ the kick drum or rest of the music. Using a headphone amp with these and that greatly increases bass resolution and texture, but did nothing to make the bass integrate with the music better.

I recently moved to the Ultimate Ears UE-5C, which are about $200 more expensive, but clearly superior in musicality, tone, detail, smoothness, bass texture, and comfort (IMHO). I actually find myself wanting to listen to my iPod w/ the UE-5C's even when I can listen to my Sennheisser HD650's on my expensive main system. When listening to the UE's, it's never an effort to hear how all the musicians are playing together, and I always feel a distinct sense of loss when I take them off and stop the music, which is not something I felt when taking off the Etymotics.

Still, if you can't swing the extra $ for UE-5C's, these are worth every penny. For me, I would wait a few more months to purchase the UE-5C's, which are already custom fitted.

Strength

Super portable, nuetral sound, great isolation, especially with custom-fit sleeves. Pick these anyday over active noise-cancelling phones. Worth the money.

Weakness

Bettered by other, more expensive phones. Bass lacks texture and impact, and is sometimes disconnected from the rest of the music. If you wear them while working out, the sound of your own heartbeat and breathing can be overwhelming! Microphonic cord, so use the clip to minimize this.