When I first heard the Hifiman RE600S in-ear headphone in the summer of 2013 it blew me away. The sound was super clear and the imaging was expansive. I also loved that the RE600S' gloss black finished aluminum ear pieces were incredibly tiny and lightweight, so comfort was excellent. But it was the transparency that kept me coming back for more. So when I'm not working on an in-ear headphone review I usually take the RE600S with me when traveling around New York City.
The RE600S is all about clarity, there's no bumped up bass or overly bright highs, the sound is unusually clear. Stereo imaging is broad and spacious in ways that no other comparably priced Beats, Klipsch, Shure, Sennheiser or other in-ear headphone can match.
The RE600S has 8.5mm titanium Hifiman designed and manufactured drivers, the headphone's impedance is rated at 16 Ohms, and sensitivity is a little higher than average at 102 dB/mw.
When it was priced at $400 the RE600S was more expensive than what most non-audiophiles would pay for an in-ear, and that's why I so enthusiastically recommended Hifiman's $79 RE400 as the perfect entry-level audiophile in-ear 'phone. I still think that one's a great buy, but now that the RE600S' price has dropped to $200 it's within reach of a lot more people. The RE400 and RE600S are available from Hifiman and Amazon.
With this sort of radical price drop you might conclude that a RE600S replacement model is imminent. I would guess so, but Hifiman hasn't released any information to confirm that.