See above

KZ knocked it out of the park here. This headphone basically sounds like an excellent mid-tier $150 headphone that has a cold.
 

1. There's sub-bass rumble that most cheap headphones completely disregard -- albeit it's not super refined.
2. The bass is well-controlled and has fantastic texture without being boomy.
3. The midrange is very similar to the RE400 with beautiful clarity and crunch to guitars, and a melodic lilt to voices -- though it's not quite as clear in the upper register as, say RE400.
4. The highs are very much present and not at all sibilant, but can take a backseat at times.
5. The energy the HDS1 presents is very punchy and dynamic -- where most cheaper headphones sound relaxed or "laid back".
6. Very wide sound stage with great imaging and instrument placement for the price -- of course in complex passages it gets muddied a little.

 
If you can imagine the concept of an Aurisonics Rocket or Ortofon e-Q5 with a "cold" or that sounds "not quite the same as you remember" or some other handicap that lowers its overall level of refinement, you have a perfect concept of the KZ-HDS1. And that's really incredible when you think about it -- a very well-made, attractive headphone that sounds "similar" to $100-$200 IEMs -- for just $8.

There's a lot of different companies trying to earn your ~$400-500 in exchange for a shot at upper-middle class audio bliss. Audio Technica did a pretty good job here. There's not really anything I can fault aside from the level of detail and sub-bass not really comparing to my FLC8S, though doing quite a bit better than an older four-driver IEM, the Westone W4. It's a perfectly respectable way to sink your teeth into multiple drivers, even if not a guarantee to be the best you'll ever hear.

This IEM is a complete game changer. Prepare to be upset by your recent $500+ purchase, or thrilled that you held out for something truly worthwhile. You don't know who FLC Technology is -- good. The surprise is worth it. Just buy it. Don't wait for me to write a more complete review. I might, but I'll probably be too busy listening to these IEMs. Check out the wise words written by other reviewers on this page. Do it. Buy them. You are being peer pressured. Submit.

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!

There's an extremely vibrant, rich sound that they produce. It sounds far better than any other earbud I've ever used, and better (and equally as spacious/open) than most on-ear open headphones I've used before. Unfortunately the fit is difficult for people with smaller outer ears (me) and while they sound great just sitting there, I need to hold them in place with the speaker directed directly at my eardrum for best sound. It's probably going to sound better and better the bigger the size of your cochlea. I can DEFINITELY hear the potential, and for the cost, you'd be stupid not to try them.

I was so excited to finally get my hands on the holy grail of mid-range headphones, the Sennheiser HD650... or so I was lead to believe. 
 
Facing facts, we're looking at a relic here. Whether that relic should be viewed through the lens of history as a valuable antique, or as a laughable remnant of a more primitive society, is the question that's up for debate. I vote for the latter. This headphone is soon to celebrate its thirteenth birthday, and in the meantime, the rest of the world has progressed unrelentingly. At one time, the HD650 may have had the chops to compete in the mid-range arena. It was probably viewed as a spacious, warm, bassy "upgrade" to its sterile cousin, the HD600. The fact that it could take a lot of energy from an amp and increase in overall speed and technical precision with the added energy was probably fuel for the fire for gear-collectors and upgrade-addicts.
 
The problem is, when you try to polish a turd, you just get a shiny turd.
 
Alright, I'll be as neutral as I can be starting now. This headphone is a good technical performer with speed, detail, sound stage spaciousness, instrument imaging, and overall can make anyone go "wow" once or twice in a listening session. For $499 MSRP, it had damn well better. Unfortunately, like a fireworks display, you just spent a ridiculous amount of money on something that made you go "ooooooOOOhhhh!" once and then ceased to impact your life in any way for the rest of eternity -- aside from the lightening of your wallet. The exaggerated warmth in the bass and completely lifeless, sucked-out mid range is as quick to take the wind out of your sails as a punch in the gut. I couldn't believe what I was hearing -- side by side, the HD650's little brother, the HD600, had so much more vibrancy and actually made you pay attention to the music. The HD600 had no problem effecting an extremely tight, natural-sounding bass note. The HD650, on the other hand, bloomed the same note to a point where it was impossible to believe they were built on the same stock. The voice (especially male voices) ability of the HD650 was a total downgrade. It literally put a frown on my face to hear my favorite music rendered in such a dull and distant manner, when retribution was only inches away in the form of the HD600. I played both through an excellent $250 amplifier and I refuse to be lead astray that, if only I put another $1000 into the amp chain, it would have started to sound good.
 
Why do people like this headphone? Because it used to be the bassy/warm version of the best headphone going -- the HD600 -- and people like bass? I have no idea how this phone was Sennheiser's  flagship for so long. They completely turned the HD600 on its head and ended up with a monster. It took a pinch of the original technical prowess of the HD600, added a metric buttload of warmth, bloom, lack of intimacy, and sadness; and completely took away the charming and realistic voicing of the HD600.
 
The biggest disappointment is the price and the previous flagship status of this headphone. If the HD650's MSRP was $199, it could get a hearty recommendation for people who crave warmth and don't really look for realistic sound. If they called it the HD500 it might have made sense. As it stands, it is a stain on the history of a solid company. Compared to literally every other mid-range headphone that I've tried that is more modern (Fidelio X2, HE400 to name two), the HD650 is an afterthought.

Love 'em! Great if you can get them for a more reasonable price (sub-$300). The perfect definition of "upper middle class" sound, with a special punch in how natural the bass and mids sound.

PRO: Great imaging, instrument separation, mids and bass clarity and quantity. Can easily beat most of the $100 and under IEMs I've heard. Immense detail for a "bass-adequate" IEM.
 
CON: Treble rolls off a little, but not in a poor way. Flat J-cable. Sound stage is not small, but smaller than an IEM it sonically competes with, the Sony EX600. A little distortion at moderately-high volumes.
 
Beats the Yamaha EPH-100 a bit. Wrecks the Vsonic GR06.
 
Props to ClieOS.
 
http://www.head-fi.org/t/632892/review-sony-mh1-the-best-kept-secret

Incredible bass in quantity, quality, clarity, everything. Easily as good or better than all other contenders at this price range, I don't care who they are. Midrange still has great presence. Sadly, the treble is kind of crummy, and it made me sell them. The treble is worse quality on the EPH-100 than on the Vsonic GR06, while still having a similar sound signature, and the Vsonic GR06 is 1/3 the price. The EPH-100 perform better in all other aspects, including fit and build quality, but only a little; and the treble issue is too much for me to overlook. I guess I'm a bit of a treble-head.

There's a saying, "80% of the quality for 20% of the price". That kind of ratio is hard to find in the audio world unless you're comparing very high-priced items, but in the budget IEM realm, these are as close to that phrase as possible. They have a very similar signature to both EX600 and EPH-100 with about 80% of absolute audio quality, and are less than half price of either. Sound staging is great with forward mids and bass, though the treble is still alive and kicking, just less-so. That's not even to mention the excellent assortment of accessories that Vsonic gives you with just about any IEM they produce. A big feature in this IEM that I don't notice in others is super-strong note preservation in the lower register. Bass notes seem to go on forever in a great way, but never overpower the mids or sound muddy. Sounds like you're right next to an acoustic instrument like bass viola, piano, etc.

These headphones have it all for the price. I've never heard anything like them at this level. They have a clear, balanced sound with all frequency ranges represented fairly equally, with mids and highs ever so slightly forward compared to bass in "clip-on configuration". If you mod them with a PortaPro or Parts Express headband, the drivers are pushed closer to your ear and give a bit more bass and mids.
 
The main thing that stands out with these is a simply silly amount of instrument separation. Everything sounds like it is popping out of a pure-black background -- think of turning the contrast up on your TV or monitor; or more correctly, adjusting the gamma level. This lets you analyze tracks very easily, useful if you're a musician. A downside to this is that they don't sound too "cohesive", and music can sound a little hollow, flat, or broken-up. Don't confuse this in any way with "dull", though, because they are full of energy and never fade into the background, while still not being harsh.
 
A fairly unique sound in absolute terms, and a steal at the price. The only downside is the comfort of the clips; I could never get them to feel great, but they were at least functional. Good work Koss.

These are a steal at $10-15. Their sound signature is about 5/5 bass, 2/5 mids, and 4/5 treble -- in strength/presence. Voices sound distant and a little quiet, but bass is very intelligible and surprisingly articulate for the price point. Treble is present much more than mids, and add to a general V- or checkmark-shaped signature. A wide soundstage also comes with them, which shocked me. Both vertically and horizontally, a lot wider than average.
 
Of course, the detail isn't impressive. There's a considerable amount of fuzz/"blur"/smearing in any intricate passages, especially in the mids. But this is to be expected at $12, lol. Their signature itself is still pleasing (and I don't even like V-shaped signatures). They almost sound like if there were a cheaper, lower model of Monster Turbine; this is where they would fit in. For any rock, you're going to be really happy with their presentation. Rap, because of the dependence on vocal presentation, is going to suffer a little, but the bass kick will still add enjoyability. I wouldn't get these for pop or classical tastes. But I don't really believe in recommending phones based on genres anyways; a good phone is a good phone. Isolation is just OK, and same with microphonics -- basically every Meelec IEM ever has microphonics issues. Not a big deal to me.
 
These are the perfect "throwaway" set of IEMs (if you're feeling so cavalier about money as to be able to think that). I can wrap them around my player and take them everywhere and not really worry. Definitely the best sub-$20 IEMs I've ever listened to, including other Meelec offerings. They can't really hold a candle to anything $30-40, especially in instrument separation. But for the price, you definitely get your money's worth.
 
4/5