Before I begin, I'd like to thank the representative from Shozy for sending me a set free of charge in exchange for my review. I will try and be as honest and truthful as I can in my review regardless. To be honest, when he approached me I had pretty low expectations for these since he was a bit vague on providing any specifics, he just told me he was sending me a "really good sounding IEM" and that I should burn it in before evaluation with at least 100 hours of orchestral music. 
 
My set came in a bubble wrapped bag with a set of eartips and that is it, no case or other accessories, just three sets of tips for small/medium/large ears. It looks like the final ones come with a case and perhaps some other accessories, but since mine didn't come with any of that I won't make a comment on the fit and finish of anything other than the IEMs themselves.
 
The wood housing used for the IEMs, Y split, and connector seems like it's good quality; it's not highly lacquered and then polished for days, and it doesn't look like some exotic endangered species of wood but the color and finish are both really nice, it certainly stands out a bit from the plastic fantastic crowd of IEMs at this price point. The cable is a nice feeling rubber material that's semi transparent and allows some of the strands of copper to show through, giving the cable a really sleek look when you really start looking at it. Microphonics on the cable are still certainly present, even when being worn over the ear, but they aren't too loud I'm guessing a slider would have alleviated this problem but my set did not come with one. The cable seems to have a small amount of memory to it, so trying to straighten the cable out all the way after wrapping them up for a while might be a challenge, but this shouldn't be a problem for most.
 
The housings are fairly tiny and fit very well into my ears. Then again, I have big ears and my go-to IEM for the last two years has been the Sony XBA-H3, which is much bigger, so I might not be the best person to judge fit from.   Isolation seems pretty good for a dynamic IEM but without aftermarket tips that go deeper in the ear canal they certainly shouldn't replace your earplugs or earmuffs in any high volume environments. I am unsure if these are ported or not but given how good the isolation is I'm going to guess they aren't. If they were it would probably be the single best isolating vented IEM I've ever heard with single flanged eartips.
 
Before giving my sound impressions, I just wanted to say that originally the rep didn't give me any pricing info for these until I asked, but I genuinely thought the asking price for these was going to be somewhere in the $100-200 range. When he told me they would be $50 I was pretty flabbergasted.
 
Now onto the sound. Going from bottom to top, the bass on the Shozy Zeros has good punch and great extension; it never felt like it was overpowering any other parts of the sound spectrum but it is definitely very present. I would say the bass has more of a rumble than a punch, which I believe suggests it's a bit more focused in the sub bass than mid-bass area. The extension is really good too, going at least as deep as my budget subwoofers in my car and home theater setups. Either way I was really impressed with the bass and it was probably my favorite part of the sound. 
 
The mids always seem the hardest for me to gauge on IEMs, but here they seem to be well balanced; they aren't heavily recessed or anything and I was able to hear a good amount of information in the range, but they also weren't crystal clear either. I would say some vocals and instruments sounded clearer on my H3s than the Zeros for example, but only by a bit. That may be related more to the treble than anything though. In summary, there's definitely nothing weird going on in the midrange, everything is pretty much where it should be.
 
The treble sounds pretty great too. This is where I feel like a lot of IEMs fail for me: they're either way too treble happy and end up giving me a headache after as little as a few minutes or too soft and dull sounding for fear of sounding like the former, or perhaps to mask treble peaks that they didn't bother fixing. Either way I am happy to say that the Zeros don't have any of these issues and the treble is pretty well balanced. While it does lie on the softer side, there is still a good amount of presence and it sounds more refined than a lot of other cheaper sets of IEMs I have laying around. The Zeros check that very rare mark for me since they don't sound too bright and painful nor too soft. Very few sets I've heard under $150 achieve this as well as the Zeros.
 
So perhaps it's because my sound preferences just align with the Shozy Zero's sound signature, but I really think these are a winner. To me, these IEMs sound like they are worth twice to three times the asking price to me.
 
Equipment used:
Nexus 6P 
Project H: Some Chinese CS4398 DAC combined with an Objective 2 amplifier.
 
For an idea of the kinds of music I listen to, you can look at my last.fm page but in summary I listen to a lot of Japanese music: EDM, anisong, pop, etc along with some American classic rock and miscellaneous other tracks from classical to rap.
 
Again, thanks to the rep and please let me know if anyone has any questions about my review.  

First of all, I would like to thank DUNU for choosing me as the winner of a contest to receive a free pair of DN-1000s. 
 
The DUNU DN-1000 is a part of a relatively new and evolving class of IEMs, known as “hybrid” IEMs because they have not only balanced armatures but also dynamic drivers inside. In most cases, the dynamic driver is assigned to the bass, and the balanced armatures to the mids and treble. The DN-1000s are no different. It’s hard enough to make a good sounding IEM using just a dynamic driver or one balanced armature; adding more drivers (especially dynamics and BAs mixed together) has more of a risk of ruining the sound quality, but has bigger rewards such as better high/low frequency extension and better overall sound quality. From what I can hear, the DN-1000s definitely fall in the latter category.
 
What’s in the box:

The box for the DN-1000s is fairly bland and Engrishey, but the amount of accessories they include in the box is simply staggering. While it does kind of feel like they just threw a bunch of tips in the box without fully testing them to see how they affected the frequency response of the IEM, or if they even fit at all (the foam tips were really tough to get off the IEMs, and I received three medium tips of one type, and only one large tip), you shouldn’t have a problem finding some tips to fit your ears.
 
Build Quality:
The housings on the DN-1000 are some sort of shiny metal. It doesn’t feel like it’s made of any particularly indestructible material, but it also doesn’t feel like wrapped up tin foil either. The housings are relatively large, and do stick out of your ear a bit. I wouldn’t sleep with these in my ears, and I would also advise those with smaller ear canals to try and demo these before purchasing, because the shells can be quite large and obtrusive, especially if the included rings are not used.
There is a complete lack of any sort of rib to help hold the tips on the IEM shells (probably so that the o-ring system could be implemented), which makes the tip rolling for the DN-1000s quite limited. If any other tips are used and you can actually get them on the bore, they will probably fall off. I will also go ahead and say it now, but I think the o-ring system is a good idea in theory, but without them, there is no way these will be comfortable in very many people’s ears. They still aren’t the most comfortable to my ears, but they are tolerable for a few hours.
The cable is the same one I’ve seen on the DUNU DN-23s. It’s not very thick and feels like it may eventually break, but it’s nice and soft and doesn’t retain very much memory. The strain relief on the housings is fairly small, but it looks like it should do its job. The Y-split is nice but has no strain relief on either side. The 3.5mm connector is 45 degrees, and while this isn’t my favorite angle for a headphone connector, it’s implemented fairly well. The strain relief allows the cable to bend a fair bit while also doing its job, so it could theoretically be bent into a 90-degree connector.
 
Isolation:
The isolation is above average for dynamics; I don’t see any major vents letting in a lot of outside noise, but since tip rolling really isn’t an option with the DN-1000s, I wasn’t able to try out Meelectronics tri-flange tips to really push the isolation to the limit. And honestly, with the bi-flange tips included, I thought the DN-1000s didn’t sound as good, so I never bothered seeing how good the isolation was.
 
Sound Quality:
Please note that the following sound quality impressions were taken with the single flange reinforced gray tips and red spacers.
 
Bass:
Most IEMs I’ve heard that use balanced armatures don’t quite deliver enough punch for my tastes. The bass on the DUNU DN-1000s, however, is delivered by the dynamic driver. It’s a bit north of neutral and has fairly good punch, but generally stays in the sub-bass in the form of rumble. The real bass emphasis ends at the lowest notes of a bass guitar, so kick drums and deep bass lines on electronic, and the rest of the bass is fairly tame and controlled. I never heard it overpower or bleed into the midrange, probably because that’s where the balanced armatures kick in. This isn’t the most detailed bass, but it’s very fun and good for on-the-go listening.
 
Midrange:
The midrange is, for the most part, right where it should be. Instruments fairly natural and don’t sound distorted or out of place. Male vocalists sound clean but have the appropriate amount of heft to sound natural. My only complaint would be with the upper midrange and lower treble area, where female vocals are prominent. Like all the other TWFK IEMs I’ve heard, this area sounds a bit soft, and while female vocalists don’t necessarily sound recessed, they are lacking a bit of clarity and texture. This is a very common area to place a dip in the frequency response though. It seems for whatever reason that a lot IEMs put a cut in this area of the frequency response or have a painful spike further up in the treble response. Given the choice, I’d much rather take the dip in this area.
 
Treble:
The treble is similar to the other TWFK-based IEMs I’ve heard and owned, such as the Heir 4A, Ultimeate Ears UE900 and Brainwavz B2. The first two are what I would classify as properly dampened TWFKs, with the latter being an example of an improperly dampened TWFK driver. When there isn’t enough dampening on the TWFK driver, there is a sharp spike in the 8-10k area that is quite painful to me and makes sibilance quite bad on most recordings that have any form of it. However, both the UE900 and 4A are dampened enough to dissipate this spike while retaining enough of an emphasis in this area to sound dynamic and exciting. So where does the DN-1000’s TWFK dampening lie in comparison? To my ears, they use almost exactly the same if not the same filter as the UE900s. While the treble isn’t quite as extended as in the UE900, the rest of the treble area sounds quite similar, which is great for the most part. While it does mean that in comparison to the bass and midrange the treble is a bit softer overall and isn’t the most detailed or clear sounding treble, it still retains enough of the 8-10khz elevation to sound “dynamic” and relatively clean and clear. While it doesn’t have the same detail level as some other IEMs that are brighter overall, it doesn’t lack clarity by any means, and those other brighter IEMs are either painful to listen to for long periods of time, or simply don’t have as much bass.
The only disadvantage to this TWFK treble is that sometimes the 8-10khz peak area can make some tracks sound a bit “steely”, or simply a bit artificial when compared to IEMs that do not have as much emphasis in this area.
 
Soundstage:
To me, the DN-1000s have a fairly decent soundstage. It’s nothing that will blow your mind or make you think you’re listening to speakers, but it’s also better than the lower end IEMs I’ve heard at portraying a sense of space. I generally don’t write very much about soundstage though, since most of the music I listen to doesn’t have very much soundstage, and in-ear headphones have always sounded like in-ears to me…
 
The complimentary forum post can be found here: http://www.head-fi.org/t/700957/dunu-dn-1000-review
 
~More to be added later, including any comparisons anyone wants me to make to anything I own~

I would like to greatly thank Fiio for giving me the chance to try out their new cables.
 
Personally, I found it quite interesting when I heard Fiio, who I had always thought of as an amp and DAC company, was making cables. I received both the RC-MH1 for the Phillips X1, Sony 1R series, and V-Moda headphones and the RC-UX1, a 3.5mm extension cable.
 
While I don’t any of the abovementioned headphones that the RC-MH1 was made for, I do own multiple V-Moda cables for my modified Fostex T50RP headphone and I was curious to see how the RC-UX1 worked with my T50RP, and how it compared to the V-Moda cables I own.
 
Both the RC-MH1 and RC-UX1 both share the same Furutech cable and aluminum connector on the end that connects to your music player or amp. The cable material itself is soft and flexible, but highly prone to memory, as I demonstrate in the picture below:

(This is what happened after I wound the cable around my hand and placed it on my bed.)
 
The connectors are a nice brushed aluminum though, and the textured portion makes it easy to unplug from devices. The strain relief is good without being excessive. While it doesn’t bend very much when the cable is pulled at an angle, it seems like it will do a good job keeping the cable from being pulled out of the connector.

 
The female end of the RC-UX1 is plastic, but it’s a durable feeling plastic. Unlike some of the cheaper 3.5mm extension cables I’ve had before. Although you can see the molding where the two pieces of the connector were fused, it is much less noticeable than some of the other female 3.5mm connectors I’ve seen in the past.

 
If I had one complaint about the connectors, it would be the headphone connector for the RC-MH1 and how excessively long it seems. I’ve used the V-Moda M-100 before, and seen @miceblue's set using the RC-MH1 cable; the connector seems excessively long even for that. So much so that you could bump it with your shoulder while wearing them without much effort.

 
Comparing the RC-MH1 to the V-Moda audio only cable, the V-Moda is softer and more flexible, but to be honest, I’ve never liked 45-degree angled connectors that much, which is what one end of the V-Moda cable is. To me, it’s just a compromise between a straight connector and a 90-degree connector that feels awkward no matter how you use it. I much prefer the Fiio’s straight connector over the V-Moda. The V-Moda cable is also much less prone to microphonics, but that is because the cable is covered in a material I can only closely describe as shoelace material, which some people may find annoying.
 
I will go into sonic impressions later when I have all of my reference gear available. While I haven’t heard a night and day difference with my T50RPs, and I don’t think I will when I do compare them, any headphones that sound better with a lower output impedance may improve with the RC-MH1. When I measured the RC-MH1’s impedance in comparison to the V-Moda audio only cable, the impedance was about half (~4 ohms for the V-Moda, ~2 for the MC1). Don’t quote me though, because I don’t have my multimeter with me to verify.
 
In closing, I think Fiio did a nice job with the cables overall, despite the microphonics and wire memory. If the stock cable on your headphones break, or you need a nice extension cable, these fit the bill. I also think Fiio may want to consider making a version of this cable with a right angle connector that could be used with the Fostex T50RP, since most people dislike the stock cable, and the closest replacement available is the V-Moda audio cable, which is not idea since it has a 45 degree connector, as mentioned above.

First off, I would like to thank RHA for providing @C.C.S.. and I with review sets. I would also like to thank C.C.S. for nominating me for the review sample.
 
Gear used for review:
PC → Project H (Custom Cirrus Logic CS4398 DAC and O2 with OPA2134 opamps)
iPod Classic → Silver LOD → Fiio E07k
Galaxy Nexus
Nexus 4
 
Inside the box:
The box looks very nice and professional overall:

 
 

 
 
Inside the box, you get a great set of accessories. There are six sets of single flange silicone tips and three sets of bi-flange tips, all included on a nifty metal card that helps you keep track of all the tips:
 

 
 
There is also a nice semi-hard case that has space to put the tip card in, as well as the IEMs themselves:
 

 
 
The cable on the MA750s is relatively thick without feeling too bulky. It feels like it won't be tearing anytime soon. The length is pretty standard for most IEMs. For me, this means they're a touch too short. However, I am 6'6” or roughly 198cm tall, so this shouldn't be a problem for most people.
Even though the MA750s are meant to be worn over the ear, there is still a small amount of microphonics from the cable if you do not use the cable cinch at the Y-split to keep the cable from flopping around against your neck while walking. Once you properly adjust the cable cinch though, microphonics are almost nonexistent.
 

 
The strain relief on the connector and the IEMs themselves is excellent.
 

The Y-split seems well built just like the connector. The strain relief for the Y-split is relatively short on both sides, but it feels adequate enough.
 

 
 
While I generally dislike ear guides, I really like the ear guides on the MA750s. The ear guides are not removable on the MA750; they are built into the cable and if someone would try to remove them, they would probably end up with bare wires. This is fine by me though, because unlike a lot of the ear guides that you can snap on with lower end IEMs, or those included in higher end CIEM cables that have very little give to them, the MA750 ear guides have enough flex in them that the weight of the cable will pull the ear guides down and contour to your ears. They seem more like a subtle hint that you should wear the MA750s with the cable over your ear than a potential obtrusion.    
 

 
 
The build quality of the IEMs themselves is top notch. The aluminum shells both look and feel classy and durable.
 

 


 
Isolation is also fairly good on the MA750s. Once you get a good, deep seal (preferably with multi-flange tips), these do drown out most of the background noise, even when I have the volume low (which I usually do to try and avoid hearing loss). They still lag behind balanced armature sets I’ve had, but like most dynamic driver IEMs, the MA750s have a port that allows the dynamic driver to move air, limiting the maximum isolation possible.
 
Now that I've covered the most of the other stuff about the MA750, let's get to the sound, shall we?
 
Bass: The bass on the MA750 definitely north of neutral, but not overbearingly so. There is a good punch for most modern recordings, that still sounds coherent with bass guitars and things that aren’t meant to go boom. It occasionally bleeds into the lower midrange, but nothing too severe. I think the quantity is perfect for on-the-go listening. The quality is impressive. Bass guitars never sound muddy and are almost always discernable from the rest of the mix.
 
Mids: The midrange is, for the most part, balanced nicely in between the bass and the treble, except for a small spike and/or ringing in the upper midrange at approximately 5 kHz. This also adds a bit more detail to the overall sound spectrum though, and there are worse places to have a spike. For the price, you probably can’t find anything that has any part of the sound spectrum other than bass without some sort of spike or a complete lack of upper mids or treble, so this is forgivable, especially when you consider the severity of some treble spikes on other similarly priced IEMs.
Instruments generally sound fairly clear and coherent, probably as good if not better than most IEMs in its class, especially after some EQing, but I’ll touch on that later. Generally, most instruments have a good balance between being detailed without being harsh.
Male vocalists have a nice tonality with plenty of body that never makes them sound thin or unimpressive. Female vocalists on the other hand sound relatively soft and ever so slightly veiled. Some female vocalists, especially those with higher pitched voices, can be affected by the aforementioned spike, though generally it’s pretty minimal.
 
Treble: I am personally think the treble good on the MA750s, especially again considering its price. Most of the other “basshead” IEMs I’ve heard (Pretty much anything that had any bass response even remotely above neutral) have either completely lacked treble, or had way too much of it. In the case of the MA750, there seems to be a bit of a downward tilt with the treble, though not as bad as similar IEMs I’ve heard, such as the DUNU DN-23, Sony MH1C, and Monoprice 8320. The treble is mostly free from harshness or sibilance, but lacks a bit of treble extension for my tastes. Those who prefer a slightly darker presentation will quite like the treble presentation of the MA750. Once you apply a bit of EQ, the treble really shines.
 
Soundstage: The soundstage on the MA750s is impressive. I didn’t think it was possible with a bass-tuned IEM, but the soundstage is actually fairly open sounding. No, it will not sound as open as open-backed headphones, but for IEMs at this price point, the soundstage is really good. Better than any of the aforementioned bass-tuned IEMs I’ve heard in the past.
 
Tip Rolling: I liked the stock tips that came with the MA750, but in the end I preferred tips with a slightly wider nozzle opening, as this almost entirely negated the spike I mentioned earlier. I don’t know where they came from, but I had a pair of bi-flange tips laying around that had a slightly wider bore size and fit the MA750 like a glove.
 
In conclusion, the MA750 is a great IEM overall for $120. I don’t have a lot of experience with the ~$120 IEM market, but if one of my friends was looking to buy a pair of IEMs in the price range, I would steer them towards the RHAs. They have a great consumer oriented sound that doesn’t do very much wrong and will be appealing to most folks, especially the “beats” generation looking to get something better and cheaper.

First off, I'd like to thank Rocky for the chance to review the Dunu DN-23! I received this set as a free review sample I get to keep.
My equipment I'll be used is my Project H Amp/DAC consisting of a custom Cirrus Logic CS4398 DAC and an Objective 2 amp with Burr Brown OPA2134 opamp.
My last.fm profile can detail the music I generally listen to: http://www.last.fm/user/mechgamer123
It consists of classic rock, indie rock, modern rock, classical, anime OSTs and music, Jpop, and some electronic thrown in the mix.
 
I'll start off by talking about the packaging and build quality of the DN-23s. Pictures speak a thousand words, so here are a few thousand words:

The front of the box reminds me of another headphone company that I won't mention, but I won't nitpick the box too much. Not like anyone stares at the box of their new headphones very long before diving in!
 

Inside, we get an excellent set of accessories including two carrying cases! This is the first time I've seen an IEM with two different cases!
 

Lots of tips included in the package as well!
 

---

Onto the IEMs themselves:

The build quality of the housings is very nice. They definitely don't feel like they'll split in half any time soon. The cable can be a bit microphonic at times though.
 

The Y-split seems to be made out of aluminum or some other nice metal, and is definitely excellent. While I'm not a huge fan of 45 degree angle connectors, I'll save my rant for another time and say the 3.5mm connector is good as well.
 

---

 
A quick note about isolation as well. These have the best isolation of any dynamic IEMs I've heard in recent memory. This of course depends on which tips are used. With Meelectronics' Tri-flange tips installed, isolation is absolutely stellar.
 

---

 
If I were to summarize the DN-23's overall sound signature, it would be punchy bass, clear mids, and fairly smooth treble. There's not a lot of distortion I can pick up either, which is excellent.
 
The bass on the DN-23s is north of neutral, but not overbearingly so like the atrocity that is the Wooduos. The bass delivers a nice fun punch while not totally overpowering the mids. The bass boost stays mostly in the sub-bass, but also goes a bit into the mid bass as well. It's definitely an excellent bass that's great for listening on the go.
 
The mids on the DN-23 are pretty good as well. They're not recessed or forward, just the way they're supposed to be.
 
The treble is where things go awry. First off, there's a slight treble spike somewhere in the 6khz area that can make some recordings with female vocalists slightly simbilant. Also, as with all the other bassy IEMs I've heard, the high frequencies are lacking. After 14khz, it starts rolling off quite a bit.
 
Both of these problems are easily remedied though. Changing tips can affect the severity of the 6k spike, and for this reason I'd recommend using the bi-flange tips included in the package, or some Meelec Tri-flange tips. With either of those, the spike is quite minimized. The Tri-flanges also make the bass a bit louder than the bi-flange tips as well. The high frequency rolloff can be fixed as well with EQ. On iTunes, boosting the 16k band by 8-10dB. Once you do this, you get an excellent IEM that's neutral with a bass boost.
 
In closing, the Dunu DN-23 is definitely an excellent IEM for the price. The sound signature is easily likable, and the included accessories are very nice. I'd definitely recommend them if you're a basshead and don't mind a bit of high frequency rolloff (or are willing to do some EQ).

First of all, I must thank Bowei006 for lending me the E07k. I won't be going into the sound quality all that much in this review, but will instead go over the physical characteristics of the E07k.
The overall design of the E07k is very refined. It looks better than both the E7 and E11, which I have owned at one point or another. 
 
Picture Time:
The front of the E07k is mostly glass, with a snazzy bezel, and piece of metal running along the bottom.

 
The back continues the same brushed aluminum as the front and sides of the unit:

 
At the bottom is a mini USB-in as well as a line in, and Fiio's proprietary line out, which can be used with the E09k as well as the L7, for a DAC line out.
 

 
 
At the top are two headphone jacks, which is a very nice feature that I've actually used a few times already. It's great for bus rides where you have two people listening to the same song or trying to watch a movie together.

 
On the right side is a lock switch, which is another great inclusion on Fiio's part.

 
Then on the right side, we have the volume buttons, as well as a menu and Power/Exit button:

Fiio had another great idea with the volume buttons, which is that it takes to clicks to change the volume, preventing you from accidentally bumping the volume buttons while wearing IEMs and blowing your ears out.
 
A Quick Note:
I found that the size of the E07k was perfect with the iPod Classic. Using the GR07 and the L9 cable, the top of the right angle GR07 cable matched up perfectly with the top of my iPod, while the bottom of the L9 was level on both the E07k and the Classic.
 
User Interface:
The overall UI of the DAC is still very basic, like it was in the E7. It controls the volume, channel balance, gain level, and other settings, such as a sleep mode, and the option to change how long the screen stays on after a button is pressed. The Orange menu bar really isn't to my liking, I believe it would look much better in a blue that matched the LED, but this is just my opinion.
 
Sound: (Objectivists look away now)
As I said before, I won't be diving into the sound aspects of the E07k too much, both because I don't have very much equipment to compare it to, and because I am unable to do proper volume matching, which I believe might be skewing my opinions. Nonetheless, here goes.
My "reference equipment" if you will, is an iPod classic 6th generation, and an objective 2 amplifier. I was able to compare DACs fairly straight across, and I believe that there are subtle differences in the vocals between the Cirrus DAC in the iPod and the Wolfson, the vocals felt more intimate, while being slightly more edgy and harsh. The Cirrus felt smoother, but less intimate. I wouldn't say one is completely better than the other, they're simply different.
 
As for the amp section, I used the iPod as the DAC plugged into the line in on both the O2 and the E07k. I found the E07k to be ever so slightly rolled off in the treble, making it sound a bit warmer. Overall however, the differences are very small.
 
Power and Other Thoughts:
-Keep in mind that I generally listen to music between 75 and 85dB, which is considered "quiet", which may mean that the E07K might not be able to power your favorite headphone at 100dB, or however loud you listen-
While the E07k isn't a nuclear power plant, it has plenty of power to drive most, if not all dynamic driver headphones. The HD600s are no match for the E07k, as I can easily drive them to listenable levels at around 20 out of 60 volume points on the lowest gain. Surprisingly, the E07k is also capable of driving my Mad Dog T50RPs at around 25/60 volume points. Personally, even when conducting my brief A/B tests with the O2, there was very little audible difference in sound quality between the two.
One of the problems with the E07k that the E11 also has trouble with is noise. With a quiet background, I was able to hear hiss with the GR07s that was not audible on the O2. However, if you're out on the go (where this unit is really meant to be used anyway) the noise should be mostly inaudible.
 
I hope you all enjoyed this review, and I plan on adding more to it in the near future. Please leave a comment if you have any questions!

Wow, It's been over a year since I started my Hi-fi journey, quite hard to believe for me. Before I owned the HD600s, I had exclusively been listening to the Brainwavz B2 IEMs. I heard the HD600s for the first time in mid-July, and while I wasn't blown away at the first listen, I definitely knew I needed something other than the B2s, because the treble spike in the B2s was starting to get on my nerves. After doing a bit of research, I finally settled on the HD600s. Without further ado, here is my formal review:
The accompanying thread can be found here: http://www.head-fi.org/t/636019/review-sennheiser-hd600
 
Main equipment used in this review:
 
iPod classic 6th gen 80gb 
Objective 2
Fiio L3/L9 LOD cables
 
Musical preferences:
Classic Rock (Beatles, Stones, Steely Dan, ELO, CCR, ect.)
J-Pop/Anisong (ClariS,OPs and EDs for Anime)
Indie (Mumford & Sons, Black Keys, Awolnation, Modest Mouse)
Classical (Just starting out)
Jazz (Just starting out)
Metal (Mostly soft stuff like Metallica)
Video Game/Anime/Visual Novel OSTs
 
You can also look at my last.fm profile to see exactly what artists I listen to. Ignore the play count though, for some reason I can't get iPod scrobbles to work with the last.fm desktop app and iTunes...
http://www.last.fm/user/mechgamer123
 
Build Quality/Design:
While I don't think the HD600s are built poorly they aren't the final word in build quality. The glossy plastic material used for most of the headband feels very sturdy and durable, but the black plastic surrounding the driver does not feel quite as good. That particular plastic looks cheaper, but still doesn't feel too bad. You won't break them with everyday use though.
The overall design of the HD600s is very good to my eyes. Most of the pictures online make the blue marble finish seem way brighter than it actually was with my unit. While they don't scream durability or style, it shouldn't be enough for you to discount them entirely yet until you hear them yourself.
The cable is detachable and is very good quality. I have not and will not use anything other than stock cables, as I believe they're a waste of money.
 
Comfort:
The HD600s are the most comfortable headphones I've ever worn. Although that doesn't say that much considering I haven't listened to too many cans. The clamping force is average to me, and the headband is very comfortable to me. Even though my ears and head are relatively large, I never experienced any discomfort issues. My ears also fit comfortably within the earpads. As a frame of reference, after listening to the Q701s for about an hour, the headband would start to hurt my head.
The velour pads are also very sturdy and don't make your ears feel hot after extended use. 
 
Sound Quality:
Well, this is the big one. So far in this review you'd wonder why anyone would ever spend $400 on a pair of headphones with average build quality and good comfort! Obviously the most important part to many of you is the sound. I will try to do my best to explain the sound, but keep in mind I haven't heard any other headphones in the price range, my closest frames of reference are $150 IEMs.
 
-Bass:
The bass of the HD600s has good texture as well as extension. While sub bass is lacking, mid bass is well controlled and provides a nice punch. Bass is definitely good, although it doesn't satisfy my basshead craving. Instead, it stays relatively contained and provides a nice warmth to the sound without being anywhere close to overpowering.
 
-Mids:
The mids are the focal point of the HD600s, and they are wonderful. All of the instruments sound completely natural. The timbre on every instrument sounds awesome. While with the B2s some instruments sounded a bit weird, and some not completely natural, the HD600 absolutely dominates everything I've heard to date. This is the selling point of the headphones for me. The other thing that sold me on the HD600s was the vocals. While they aren't heavily forward per se, they are very intimate and engaging compared to the IEMs I own. I will discuss vocals more in the soundstage section.
 
-Treble:
The treble of the HD600s embodies a love/hate relationship I have with them. The treble is somewhat recessed compared to the mids, although there are various spikes which I find add a small amount of sparkle to the sound and also make the cymbals crash with some authority. But these treble spikes are only a couple decibels, and so the HD600s will never hurt your ears with too much treble if you're sensitive to treble spikes like I am. Obviously, the advantage to having laid back treble is the reduced chance for fatigue after long listening sessions as I have noted above. However, the treble is also not as detailed as other headphones that have a more balanced treble.
 
-Detail:
When listening to the HD600s, I often struggle to find microdetails in recordings such as when the vocalist takes a breath, but instrument detail is fairly well done. While I find this somewhat annoying, I find myself not paying too much attention to the small details nowadays, and instead listening to the bigger picture.
 
-Soundstage:
The HD600s are obviously open backed, so the soundstage isn't bad. While I never got the feeling that the sound was too far away from my ears, I don't feel that the soundstage is closed in at all. The soundstage is better than any of the IEMs I have tried. I also feel that the center stage is very well done. Vocals and instruments that are supposed to be in the middle of the soundstage sound much more intimate and engaging than anything I have previously heard. Overall the soundstage is above average, but still not perfect.
 
Musical Pairings:
The HD600s sound awesome with just about any genre you throw at them, whether it be electronic or jazz. The only area the HD600s lack in is genres/songs with a lot of sub bass, which is relatively quiet.
 
Closing Thoughts:
These headphones are simply excellent any way you look at them. While the build quality might not meet military standards, they should last you a long time. Besides, you weren't planning on taking your open back HD600s into combat with you, were you?
I would also like to leave a frequency response graph here so that you can draw your own conclusions about my review and the headphones themselves:

Please let me know if you have any questions or comments about my review, hopefully I will be writing more reviews on gear once my wallet gets to feeling better...

Hi Head-fi, welcome to my first ever IEM review!
I feel I should review these before getting my HD600s, because these probably won't get as much head time after that.
I picked up these IEMs used from a fellow head-fier exactly 5 months ago.
My source for the review:
iPod Classic 6G<~~Fiio L9 LOD~~>Objective 2
FLAC
70% Classic Rock
20% Jpop
10% Alternative
(Check my profile for specifics, or http://www.last.fm/user/mechgamer123)
 
Comparisons I have:
AKG Q701 (Very short listening time before returning)
Hifiman RE-ZERO (previously owned for a few months)
Yamaha EPH-100 (Very short audition)
Sennheiser HD600 (Short audition)
 
Build:
First off, I'd like to say I like the design of the IEMS. They aren't amazingly beautiful, but they're going to be in your ears, so who cares... The cable has been unraveling slowly but surely since I got it. Again I haven't really cared. The cable does look cheap, but so far I haven't had stiffening like I did with my RE-ZEROS. Strain relief is decent. I'm probably not the right person to ask about durability, because I always baby all of my tech. They haven't broken yet. That's good enough for me.
 
Isolation/Micophonics:
If you couldn't tell by the picture, they're ment to be worn over the ear, which means cable noise is nonexistent. With the stock tips, I haven't been able to get a good seal in the second part of the ear canal. Seal in the outer part of the ear canal is pretty good though. I have heard etymotic tri-flanges help with this. I will buy some when I get the chance and report back. I also tried the comply foam tips included with the B2s, and they toned down the treble and made the bass a bit more muddy. But once they wore out, I never bothered to replace them. Isolation is decent with the silicon tips and pretty good with the complies however. You can listen to music within safe levels even if you're in a loud environment. When the B2s are in the first part of your ear canal, they feel almost nonexistent. However, when I tried deep insertion I could definitely tell they were there. So overall their comfort should be pretty good for most people unless you have small ear canals.
 
Sound Quality:
Phew, here's the big one. Usually the make-or-break point for many audiophiles. I'll try and describe what I'm hearing to the best of my abilities, but keep in mind I'm relatively new to the audiophile world. Also, just as part of a personal opinion, I believe headphones don't sound their best until you've been listening to them for ~20 hours without using other headphones. Whatever you wanna say, it's like a "burn in" period for your brain. I just appreciate the strengths and notice the weaknesses most after to listening to them for extended periods of time.
Bass: The B2s aren't bass monsters. Most BA headphones aren't. But in my opinion if the track requires bass, the B2s will deliver it. It will punch fairly hard on the low end, but not to the extent that most bassheads would like. Overall I'd say it's very balanced with the rest of the sound spectrum. Compared to the RE-ZERO, there is no competition, the ZEROs have no bass. Compared to the yamaha EPH-100s however, the bass seems weak. But the EPH-100s are really a basshead IEM. So I consider these to be a pleasant balance somewhere in between. 
(instead of going on to describe the mids and highs, I will instead describe how different instruments sound, I think that's more important, and not every instrument fits into the "mid" or "treble" categories.
Guitars: This was something that blew me away from the first time I heard them. The timbre for the guitar is spectacular. Coming from the RE-ZERO, I was shocked at how much better having good timbre made songs sound so much better! The timbre is definitely better than the EPH-100, and probably slightly worse than the HD600s, but I would consider them to be on-par with each other. 
Bass guitar doesn't get it's own section... You can hear it, but it is a bit recessed compared to other instruments.
Drums: This is the point where you decide if the simbilance is worth it or not to you. These IEMs really do portray the cymbals in a very neat way. They sound sharp and completely natural. Also, most of the other drums in the upper half of their frequencies sound lifelike as well. While they don't do as good of a job on lower drums like the kick drum, the sound from the drums is still something truly awesome and very natural for the most part.
Piano: Pianos sound excellent. The timbre is mostly spot on. I can say the timbre is better than on either of the other 2 pairs of IEMs compared, but the timbre on the HD600 is better in this area by a fairly significant amount.
String Instruments: The timbre for strings is also great, on par with guitars and drums in that it sounds almost lifelike. Maybe even more than any other type on instrument.
-(Please note my "reference" song for piano and string instruments is "yasashii boukyaku aru hi no yume." The timbre of the instruments in this song really adds to the emotion of the track. It sounds epic.)
Wind Instruments: Again, the timbe makes wind instruments sound great as well. I didn't get a chance to listen to wind in the HD600, but I can see where there could be room for improvement on the timbre. Overall they still sound incredibly natural though.
Vocals: The vocals are perfectly balanced. Not forward or recessed (like the Q701). However, if your recordings are poorly mastered, some Ts and Ss can hurt your skull...
 
Soundstage: These are no open backed over the ear cans, but they do a mighty fine job in the soundstage department. You won't think everything is out of your head, but instrument separation is great and you can hear exactly where all of the instruments are.
Closing Notes on Sound: Sound quality overall is great compared to the other 2 IEMs I've compared that are in the approximate price range. Also, the level of detail of the B2s is great from what I've gathered, but I haven't really had a good listening session in a while where I just pick out details, so I don't really want to say too much about microdetails.
 
TL;DR on SQ: The Timbre is amazing, you will love or hate the slight simbilance, and the balance is excellent. Really good sound quality!
 
If you have any questions/comments, please feel free to post them!