Summary: The isolation on these with foamies is second to none, however they are not practical for on-the-move portable headphones due to terrible microphonics. Perfect for long public transit trips, or sitting somewhere, but not moving around. Soundstage is bizzare in that its quite small, but more precise than anything I've heard.
Summary: These are the 2nd pair of iem's that I have owned. At first I was very disappointed with them mostly because they do not have great base, but I kept using them anyways. After two days of listening to them I have to say that they are way better than the Klipsch Custom 2's that they replaced. I never knew how much of the music i was missing. The sound isolation is also much better than the klipsch.
Summary: Ok, this is what I think about the Etymotic ER4P headphones. I've owned them for 6 months now... this is a 100% unbiased review. I'm a qualified studio engineer, musician but not an audiophile! Overall I would say these are good headphones for listening to music, however I wouldn't recommend them to anyone other than a studio engineer. That's because the sound is flat and at times too bright for most peoples taste.
Summary: Once I got used to the weak bass impact, I fell in love with the ER4 sound. The bass is very controlled, and is actually quite deep- everything is there. The mids are amazingly liquid and free from coloration. Likewise, the treble is good without bringing attention to itself. As have been said many times, the overall sound is neutral, detailed, and analytical.
Summary: I've been incrementally moving up the Etymotic product line for several years now, from the ER-6 to the 6i, and for the past couple years I've been rocking the ER-4p. Just recently I've ditched it for the ($400 retail) UE TripleFi 10vi, but even at twice the price point, UE's best is still bested by the ER-4p in some respects.
Summary: These have been my main 'phones for several years now. The ER-4S (higher impedance version of the same product) has a slightly cleaner sound, but the ER-4P's convenience (no amp is needed) trumps this for me in most situations. The sound the ER-4P's produce is highly detailed. Most types of music reproduce well with the ER-4P's. They do surprisingly well with genres that are highly involved and complex, as there is absolutely no muddiness at all.
Summary: Note that my review is in context with a very good amp so this must be a consideration in how you take my informatio. Additionally, my listening style is light jazz, classical, vocals and country. These were my first what I call high end earphones. They continue to please me for being my portable and office headphone. They isolate very well and sound extremely clear. With good sources and a good amp these phones will please anyone.
Summary: great sound on highs and mids, just like everyone else here has stated. bass leaves something to be desired. i called etymotic and they sent me a bigger set of foam tips free of charge! would recommend to a friend.
Summary: I bought these and the ER6i set at the same time. Compared to the ER6i, the ER-4P does have somewhat better response at the low frequencies. However for overall sonic reproduction, my Bose Tri-Ports and Bose QuietComfort 3 headphones far outperform either of the Etymotics.
Here's my take on sound isolation/cancelling. My Bose QuietComfort 3 headphones do great on low frequency sounds (as they are designed to do).