I received a pair of ER4Ps today and they are the "Nuts". I am currently listening through an old Cowon D2+ and these phones are just wonderful. The sound.throughout the range is beautiful. I had reservations about IEMs because I've never had a pair that fit well and did not fall out. The ER4s, however, fit snugly and comfortably using the tips that were mounted when received. I also want to point out that, if one cannot get a good, comfortable fit with the tips supplied, Etymotics has a CIEM option whereby, you get your earmolds made, and send them to ETY. They then form a custom silicone tip for your ears. You use this tip with your existing earphones. A nice option IMO.
Thanks for looking.