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: 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).
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: 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: Though lacing in some areas these are, in my opinion, some of the best headphones for the money. Cons: though the base detail and extension is vary good, the impact is lacking. These are not headphones for someone who likes to "feel" the base in their music. These are great headphones for classical and rock music, not hip hop. The second con is the price of the filter things. $15 FOR 4! That’s a little ridiculous for a piece of plastic.
Summary: I have been using these earphones for a little over a year. Most of the people who have experienced this earphone insist that it does not produce good enough bass. In my opinion, the bass produced by these pairs are just how the musicians intended it to sound- it does not falsely "boom" it up. Moreover, it should be noted that a good seal is imperative for a good hearing experience.
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.