"Reasonably priced.Good sound and great noise isolation."4.0 starson by Marcel_Duchamp
Pros: These are ear-bud style headphones and are therefore small, light-weight & readily portable. The sound quality is reasonably good although it is vastly improved by use with a portable amplifier.
Cons: These headphones are somewhat delicate and susceptible to damage. The four wires that connect the music/power source to the transducers are very thin, and tend to break if they are flexed too often.
Summary: I have owned and used these headphones for the past four years. Overall, I am very pleased. They give a clean, neutral sound and they are a good buy. Sound quality is greatly improved by using an amp; I use a Mini Box D to boost the output from my iPod. But, the key feature that stands out is the noise isolation. It is very good at blocking out unwanted sound but the standard tips that come with the headphones are uncomfortable after an hour or so of use. Etymotic has a relationship with the company Sensaphonics that makes a custom molded sleeve for use with the phones. This makes the tiny and inconspicuous ER-4P stand out and become more noticeable. it also adds another $200 to the overall price of the headphones but I found them to be well worth it.
I should say that have had wiring problems with the Etymotic phones. The wires are very small gauge and are stressed where they all join in a molded rubber union. However, the technical and customer service people at Etymotic were wonderful to deal with. They bent over backwards to make things right, and they fixed the problem even though the phones were out of warrantee. For that reason alone I would recommend buying these headphones.