Pros - Tiny size, comfortable fit, great selection of tips, beautifully, detailed, smooth and balanced, neutral sound, zero fatigue factor.
Cons - Miserable, non-replaceable cable that inevitably kinks and shorts out.
I have been a home audio buff and proud audiophile snob for decades and have only really gotten back into portable audio gear in recent months. I was looking for a nice pair of audiophile IEM's to replace - on a limited budget - my failing, seven year old Etymotic ER-4P's. I value tonal accuracy and sound-staging, and while I want bass to be present I am not a "bass-head." Oh, and I cannot stand upper-register sibilance and harshness masquerading as "detail."
So, now you know my biases!
After doing lots of research on Head-fi, I ordered a pair of RE-600's on Amazon.com.
Sonically, I was beyond thrilled with them! They "play it right down the middle" as one reviewer put it, with a neutral yet compelling tonal signature and a way with human voices which is positively enchanting. This is one of those "I could listen for hours" 'phones. Wonderful!
Beyond that, the housings are well made and feather light. They are tiny and inconspicuous and a pleasure to wear.
I believe that the RE-600 might have actually been my end-game IEM's, if not for the fact that the lower, cloth-covered cable is incredibly fragile and prone to shorting out. In the process of coiling and uncoiling the cable (that is, taking it out of and putting it into the lovely little zipper case) the cable will develop kinks that cannot be smoothed out. Eventually, one of these kinks will turn into a short that will get worse and worse until the phones are unusable.
Lest you think this is my one-off experience, go to the RE-600 Impressions thread and skip to the most recent 8 or 10 pages, and you will read the complaints of multiple, outraged owners of shorted out RE-600's.
The nice lady who answers the phone at USA Hifiman customer service in New Jersey was unfailingly pleasant and sent me a warranty replacement pair in a reasonable amount of time, but as other owners in the above thread have noted, that's all the company will do. They won't acknowledge the problem and (maddeningly) continue to sell this failure prone "flagship" product at a not-inexpensive price. I ended up selling my replacement pair at a bargain price while making sure the buyer knew what tended to happen to these IEM's.
I'll only add that I review home audio gear on my Audio Blog and have never written a review quite this negative. I only want to spare readers of this review the kind of frustration and disappointment that I and so many others have experienced. I can only hope that Hifiman will get its act together and upgrade this wonderful sounding IEM with a decent and durable cable. I'd buy one in an instant if they did. But as things now stand, I'm avoiding their products, even their prized headphones, because I don't think their behavior vis a vis the RE-600 should be rewarded.
Cons - Build quality, quality control, warranty, customer service
Sound is on par with Shure products at similar prices. (I prefer the Shure sound but their latest offerings aren't too comfortable in my ears). So that's a glowing review on the audio from me.
But the Re-600 formed a short near the headphone jack real quick, then cable started pushing itself out of the fabric jacket in another spot (I take good care & don't abuse headphones). The company was quite rude to me & did not honor the warranty due to some weird fine print. Inexcusable, I will never consider another product from this company. They brought no joy to my life.
Pros - Incredible vocal authority and surgical imaging and detail retrieval that ranks up there with any IEM
Cons - Definitely not neutral, rolled off FR on both ends - no sparkle and no slam; Build quality is horrific for an item that was previously $400 MSRP
The midrange of this IEM is truly, truly astounding. There is probably no other IEM that I've heard that presents so much microdetail of the midrange on a silver platter for the listener to eat up. Male and female vocals come through like someone is whispering in your ear. Unfortunately, the bass and treble are really rolled off and don't present music in an even-handed manner overall. It's a good example of a specialized IEM. Much in the way there are many audio products out there to provide "XXXTraBASS" and similar marketing tactics, this is a pure and supremely enjoyable IEM for vocals, piano, strings, guitar, etc. However, you will find them quite lacking for electronic, rap, pop, chiptunes, and anything where you desire a flat FR.
Know what you're getting when you get them and they can be a lifelong keeper! Well... until they mechanically fail, which they're prone to do, due to them using the same build techniques found in $15 IEMs. I've had no issues with my pair personally, but there's no denying the dozens of others who have, and similarly with the nearly-identical RE400. In the end, you just have to know what you're getting!