Haven't heard the HF5 or S4 but from how I understand it the RE-0 should be at a different league from the other two. The highs are extremely crisp and it has that airiness and superb transparency. For Classical/Jazz I prefer my RE-0 over and above my W3, and I paid a third of that on the RE-0. You really can't go wrong with the RE-0 for those genres.
Wow what a coincidence. Two weeks ago I decided to get new phones to replace my er6is and I was stuck between the EXACT same three that you mentioned. In the end I went with the re0 (it came today). I've only been able to burn it in for about 8 hours so far but I'm loving it already (I listen to a lot of classical).
I can't say much about the other two because I have not tried them, but the re0 is a definite upgrade over er6is, if that's any help in deciding between hf5 and re0.
These iems are very special, in a way that whatever your newer or more expensive gear might be, you keep coming back to them to review your matterial and enjoy your music their way...
This is not to say they are perfect though. The major strength is neutrality and fine detail retrieval without becoming bright.
Now this is a rare virtue...you can listen to layers of music (very enjoyable with complex pieces) and at the same time the sound is so very sweet and mellow.
Voices are plain perfect. Coming from a company that designs hearing aids this is really no surprise. The gain is an extreme fidelity in human voices and natural instrument timbre.
No matter how many earphones or headphones I've ever experienced, these are top in that regard.
On the less stellar side is bass extension which I can best describe as recessed. The notes are all there, even the deepest ones, but they stay in the background, letting the rest of the spectrum express the music.
If you like a dynamic, punchy feeling that hits your stomach, well, it's not here...
Finally the recording quality is vital to the performance of these iems.
Listening to rock tracks I find pieces that sound stellar, and others sound so crap that you are forced to press FF and just go on...
I've listened to both the HF5 and RE0, along with the ER-4P, ER-4S, ER-4B at length, but not the Klipsch S4. Compared to the RE0, the HF5 had a fuller note, as midrange had more presence. Both had extended and clear treble, bass is similarly tight but lightweight. Without side by side comparison, these two would be very similar. With them compared directly, there still isn't much difference in SQ, what's most apparent is comfort and isolation.
The stock tips of the Hf5 look like the fit in deeper than the RE0, would that mean better isolation? I have dual-flange ER6s and don't find them particularly comfortable but apparently the Hf5 are better :/
Originally Posted by bcpk /img/forum/go_quote.gif The stock tips of the Hf5 look like the fit in deeper than the RE0, would that mean better isolation? I have dual-flange ER6s and don't find them particularly comfortable but apparently the Hf5 are better :/
Yes, better isolation, but less comfort if deep insertion isn't your cup of tea. Don't underestimate the importance of comfort on your music experience, if they hurt, you won't like them period.