After about 5 years of use, my old Etymotic HF2s kicked the bucket. The IEMs were stripped down to bare wire and still working! Of all the things to fail, the cable strain reducer at the 3.5mm connector was the failure point - arguably the best looking part of the old things. Anyway, once they died, I ended up rolling my Apple dual drivers (With foam supertips!) for a good couple months, the entire time wishing I had a new pair of Etys. Bonus time came around, and bonus was good! So the first thing I did was order some new Etys. I was very close to getting the ER4s, but I couldn't stomach the price difference, considering my source (Google Play Music).
Upon receiving the new HF2s, I replaced the stock brain-ticklers with a pair of medium Shure olives (My new favorite tips for these), and I've been in audio nirvana ever since. A lot of people would be turned off by Etymotic's sound signature - Most describe it as cold and lacking in low end resolution. I however find that it's amazingly accurate! The highs are extended, but not harshly bright. The mids are very revealing - Lots of microdetail - with excellent separation even in the busiest of tracks, and the low end hits are very well represented, with a fantastically quick decay. While I can agree that the vibrating bass you'd expect from a dynamic driver isn't there, the quality of the bass, along with the accuracy is unmatched. Listening to anything from dance pop to mellow indie acoustics is an absolute treat. To top it all off, the isolation, even with the Shure olives vs the brain tickler triple flanges is exceptional. Expect the world to melt away with a nice deep insertion.
As always with Etymotic, highly recommended if you're looking for a fantastically analytical and clean sound. Bassheads beware - These will give you quality, but not ear shaking quantity. Etymotic products like the HF lineup will always be a top choice in my books! On a side note, shout out to the Apple IEMs for being what they are. If you're strapped for cash, and can find a pair in the 30-50 dollar range, I found them very similar to the Etymotics, with less microdetail/clarity in the mids, and a bit more thump in the low end. On a tight budget, they're probably the best analytical IEMs out there!