Build etc

Good packaging and carry case.
Cable is manageable but slightly stiffer and larger diameter than I would prefer for IEMs
IEMs feel hefty and solid. Very well built.
Outside picks up fingerprints pretty easily.
Included tips fit well. no issues with them falling out if cable wrapped around ears. I believe they intended the cable to hook around your ears.

Sound notes:

Highs:
rolled off and smooth on the high end. Nothing offensive in the high register but they don't quite resolve all the detail.

Mids:
Slight sibilance in the upper mids, Better for male vocals. Female vocals tend to sit in the sibilant spot along with some stringed instruments. Male vocals are very detailed with lots of layers. Has the potential to get nasty with a mid biased amplifier.

Sounds mid focused. Mids are the most forward with the most clarity. Highs and lows have good clarity but not as much as the mids.

Bass:
Bass is present and tight punchy/ not overbearing or boomy. Definitely not for bass heads.
Soundstage:
Recessed fairly narrow sound soundstage sits right behind your ears. Good for hearing everything and picking out individual instruments but not very accurate.

Overall:
Seems very neutral balanced. Not warm or cold. Not quite warm enough to be an all the time listen for me. They can get fatiguing after a while due to their more neutral nature.


Other Notes:
Seems like they are pretty amp dependent and really pick up the bias of the amplifier. I wouldn't pair these with an amp that has forward mids because that's where most of the sound issues with these can be heard. They tame out fine on a neutral amp but any amp with a slight mid bias might make the upper mids do some nasty stuff.

Features
Has 4 different sound modes that actually make quite a difference and can help with headphone pairing and soundstage. Standard, Standard Headphone, Pure, Pure Headphone. To me the difference between standard and pure seems to be the high and low roll off point. The pure mode is the better sounding mode that allows more highs and lows but some headphones with harsh highs or overly boomy bass might be better tamed by the standard mode. It's worth trying both. With a good pair of headphones the standard mode sounds pretty digital due to the roll off but its great for cheaper headphones, gaming headsets etc that can sometimes sound way out of line on higher end or higher power gear. The difference with the headphone mode for each seems to be the soundstage presentation. The soundstage gains a bit of verticality with the headphone mode where it is pretty flat without it.


Sound Signature
Sounds very slightly warm. Has a high and low roll off on the very top and bottom edges and sounds a lot more digital if not in the "pure" mode. Nothing is really forward. Highs, Mids and Bass are balanced. Good amount of detail in lows mids and highs. This is one of the only units I've tried that doesn't really color the sound in any way. Its a very neutral presentation with a very slight warm bias. Has a wide soundstage but not much verticality. All of the sounds sit in the same horizontal plane. This is better with the "headphone" modes but not a strong point of this unit.


Build Quality
Over all feels solid. Almost has a rubberized texture. Does pick up dust and fingerprints as seen in the photos. Rubberized texture kinda holds on to some of the dust. Volume knob is nice and smooth. It kind of feels like one of those in between items. You can tell it's not something cheap or junky but it just doesn't quite have an ultra premium feel.

Issues
My review unit seemed to have an issue where it wouldn't come out of sleep if it wasn't used for a while when connected with USB. If there was nothing playing through it for around 45 min or so it wouldn't wake up without a power cycle. Not a huge deal but definitely something that can be fixed by the manufacturer with firmware updates.

Conclusion
Overall to me this is a well behaved and well rounded unit with good detail and a very slight warm bias. Very tame non fatiguing approach with no real outstanding characteristics to define the sound. Very easy to listen to for extended periods of time. Definitely recommended for the price

Ok so you know when there is a product out there that is just ridiculously well priced? Like you almost feel like you are taking advantage of some loop hole in the system that makes you feel bad for anyone else that doesn't use it? That would be the RE-00's. The RE-00's are spectacular sounding.... Heck if these were $100 bucks I would be writing the same review. 
 
Lets jump right in to the sound... My benchmark for headphones is the HD650's. That's the best I own and have lots of experience with them. I tend to feel that the 650's sound correct and are basically what a headphone should sound like. With that being said the RE-00's are more similar to the sound of the 650's than they are different so that right there gives them an A+. Comparatively I would say they are a little more lively in the mids and have a tad more forward highs. Can't complain about that. Biggest thing to point out here is that these sound thick and full. Not something I have found in lots of IEMS I have tried. 
 
Lets talk about each....
 
Highs - Crisp and detailed and right on the edge of smooth. Nothing harsh or sibilant but definitely not smooth enough to say easy listening or non fatiguing. They could get you after a few hours but this is a far cry from lots of IEM's that are out there. 
 
Mids - Very lively and fun. Lots of detail and quite thick and full sounding. For lots of genres with vocals and acoustic instruments this gives them a very pleasing sound but this makes them not quite fast enough for fast paced music such as house or trance. 
 
Lows- Lows are perfectly acceptable. Bass is fairly tight and present and the thickness of the mids flows down nicely to the bass. It packs a nice little punch and for my ears it is plenty. If you are happy with the bass of the HD650's or basically any sennheiser can you will be fine with these. It's not missing like lots of IEM's.... RockIt R50's/Knowles I'm looking at you. Eww. Anyways the only thing missing bass wise is the sub bass but again for anything acoustic and non modern electronic that doesn't go down that low these are great! 
 
Sound Stage - These actually have a pretty good sound stage. This is one of their charms. They don't really sound like IEM's to me... At least the ones I have tried. They sound more like a good open back headphone than any other IEM I have tried. Plenty of space. Nothing feels like it's right on top of you like some IEM's. 

I made a huge mistake when I got these.... First thing I did was plug them into my phone and try to listen to some music... Bad idea! This is one of those headphones that I wouldn't even listen to until after 50 or so hours of burn in. The sound signature of these is specifically designed for gaming. Before burn in there is a very strong harsh and unpleasant spike in the upper mids. After burn in everything smooths out but there is still an upper mid bias. Why though? For the glory of gaming of course!!! To me these seem to have a fairly close to neutral bass and treble response with a boosted mid response. With no EQ and no virtual surround sound when gaming these aren't the most fun sounding headphones but they are very accurate. The mid spike makes footsteps and enemy movements really pop out at you. I am guessing that was absolutely the intent by Sennheiser when they made these. They are vastly different from the sound signature from most gaming headsets that have loose boomy bass and boosted treble. It takes a while to get used to but after you do you won't ever want to go back if you are looking for detail and want accurate enemy placement. For me where these really come in to their own is when you use virtual surround sound software with them. The 2 I have tried are Creative SBX pro and Razer surround pro. Lots of debate on what is better but for these specifically my vote goes to Razer. The creative software does the same thing as the sound signature from the Game Zero's... It boosts the mids. With that on top of the software boost it just becomes too much and a little harsh. The Razer software doesn't really EQ the sound it just adjusts placement of sounds. That works perfectly for these. The razer software also lets you boost the bass. These respond very well to that and become way more fun with a little added low end. I would rather they be flat and require me to use the surround software to boost the bass than to try to cut it out with a boomy sounding headset. With the razer software you can get a full enveloping surround sound experience with plenty of bass and no harshness. Now on to the mic... The mic on these sounds great... If your sound card can power it up. This mic with my Creative Sound Blaster Z might have been the absolute worst mic and sound card pairing I have ever heard. In fact once I got these my 2 year old SBZ got ripped out of my PC and thrown in a box. I have a Schiit stack now so it was time for it to go anyways as I was just using it for mic in. After researching I found that headsets all use small condenser mics that need power. Sort of like regular condenser mics that require phantom power but on a lesser scale. Usually headsets run on 'line power" between 2 and 9 volts. PC sound cards put out voltage to mics usually in the range of 2-5 volts. Most gaming headsets with tiny microphones are perfectly happy getting 2v and sound fine... However the mic on the Gzeros is a bit bigger and is pretty quiet with 2v going into it. More voltage = more sensitivity with condenser mics. Creative cards appear to only put out about 2V. With my Creative Sound Blaster Z I had to max the mic volume and mic boost to get enough volume from this mic which resulted in tons of white noise. Asus sound cards tend to put out a little more voltage to mics (Around 3V) so I would pick that over a Creative card if you are considering these headphones. I would also steer clear if you have Realtek onboard audio as all the Realtek chipsets I have tested put out about 2.2V. There are a few chipsets out there that put out 4.5V and I would assume that would be ideal for the Gzeros or G1's for that matter. Still trying to find a small USB sound card to use for mic input only that puts out 4.5V to use with the mic on these. So far I haven't been able to confirm voltage for anything other than the ones I have personally tested because that information isn't published by sound card manufacturers.

I tired these for a while as a friend owns them. I have the Game Zeros and I actually like those a bit better than these. These game ones sound closest to my HD555's for gaming. They have a fairly flat and neutral sound with a decent little bass hump that makes explosions sound good in games. Being open back they inherently have a good sound stage and are pretty decent at placing enemies. They however sound a little bit veiled. Everything sounds pretty flat and nothing really pops out at you. All the details are there but you have to hunt for them a little bit. That does tend to make you turn them up a little more than other headsets. Could be a good thing or a bad thing. They have the normal smooth pleasing, non fatiguing veiled Sennheiser sound. Not to say there is anything wrong with that. They sound great for music as well and I can't say that for the Game Zero's. They pair fine with just about any surround sound software. The Razer and Creative SBX studio both sound pretty decent on these. I might actually prefer the Creative for these as it makes the details pop a little bit more than the Razer software due to the mid boost that the creative software applies.
 
This is a Copy paste from my Game One review for the mic as they have the exact same mic:
 
Now on to the mic... The mic on these sounds great... If your sound card can power it up. This mic with my Creative Sound Blaster Z might have been the absolute worst mic and sound card pairing I have ever heard. In fact once I got these my 2 year old SBZ got ripped out of my PC and thrown in a box. I have a Schiit stack now so it was time for it to go anyways as I was just using it for mic in. After researching I found that headsets all use small condenser mics that need power. Sort of like regular condenser mics that require phantom power but on a lesser scale. Usually headsets run on 'line power" between 2 and 9 volts. PC sound cards put out voltage to mics usually in the range of 2-5 volts. Most gaming headsets with tiny microphones are perfectly happy getting 2v and sound fine... However the mic on the Gzeros is a bit bigger and is pretty quiet with 2v going into it. More voltage = more sensitivity with condenser mics. Creative cards appear to only put out about 2V. With my Creative Sound Blaster Z I had to max the mic volume and mic boost to get enough volume from this mic which resulted in tons of white noise. Asus sound cards tend to put out a little more voltage to mics (Around 3V) so I would pick that over a Creative card if you are considering these headphones. I would also steer clear if you have Realtek onboard audio as all the Realtek chipsets I have tested put out about 2.2V. There are a few chipsets out there that put out 4.5V and I would assume that would be ideal for the Gzeros or G1's for that matter. Still trying to find a small USB sound card to use for mic input only that puts out 4.5V to use with the mic on these. So far I haven't been able to confirm voltage for anything other than the ones I have personally tested because that information isn't published by sound card manufacturers.

These were one of my first tries to get in to the audiophile headphone world and they were not a good choice. When I first got them I enjoyed the sound but as I got further along I realized that just too much of music was missing with these. Anything in the lows and lower mids is not there. High detail is great but I just can't enjoy music if part of it is missing due to the headphone I am using. They do have a really wide open soundstage which makes them really good for gaming and positioning in games. They are also good for movies for the same reason. If you are looking for a music headphone look elsewhere. 

I found these for a great price used and couldn't pass them up because I am going on a long flight soon. The noise canceling in these is incredible as most have said. Any sound that drones on or rumbles or is generally steady and unpleasant goes away with the flick of a switch. My first test for these was my lawnmower. They can kill the sound from it to a point where it is only a very low easy to ignore sound. Music will completely drown it out. Second test was inside a data center at work. These can almost completely kill the sound from the data center. Anyone who has been in one knows what I am talking about... Lots and lots of loud fans all going at once. Interestingly enough though you can still hear people talk with these on. They are definitely quieter but if I pause my music with them on I can still hear a co worker if they are talking directly at me. I think this is by design. They are more for canceling ongoing consistent sounds not sounds that are brief and varied. 
 
Ok now on to the sound quality. It's passable. It's good. Its not amazing or awe inspiring but it's just fine. If you hear them you would understand. 
 
Highs are smooth but a bit compressed and recessed. Very top end is missing. 
 
Mids are very smooth clean and forward. 
 
Bass is slightly muddy and a tad boomy but not overstated. 
 
Overall I would consider this sound signature to be very relaxing and easy to listen to for hours. There is nothing to wear you out. That might be exactly what Bose was going for honestly. If you think about it for this type of headphone it makes sense. Some could consider them a bit muddy sounding due to the compressed highs and the boomy bass but I really do think they sound fine. 
 
So in conclusion I feel like if you can pick up a pair of these for $150 or less they are worth it. I couldn't see spending any more on them. If they sounded better they would be worth the $300 price tag. Also as others have stated you have to have them turned on for them to put out any sound at all. If your batteries die you are out of luck. I also don't like the cable. It's a bit tangly and doesn't like to straighten out if you have had it rolled up for a while. 

I ordered these biased on the excellent reviews they received here on headfi. If you listen to anyone listen to me. These headphones sound BAD and just plain wrong. I have tried these from 2 sources now. First was my Sound Blaster Z... Completely unusable when connected to it. The highs are so harsh and sibilant that they make everything seem unpleasant tinny and just awful. Cymbal crashes will make you cry in pain, Voices will sound shrill and like nails on a chalkboard and the bass is just gone. Not there in the slightest. Completely and totally missing. Kick drumbs sound like a high pitched click instead of a full boom like they should. Its quite strange.  Using my other source Fiio e7 they are usable but just sound mediocre. It's not as clean as the Creative and the highs are cut off which is beneficial to these headphones. Either source I use the sound stage is tiny and everything sounds very thin and unpleasant. 
 
Compared to my Sennheiser HD598's and my AKG K550's they are just not even in the same ball park. I was hoping they would sound a bit like the 550's but they don't they just sound awful. 
 
Lastly the cords with the way they wrap around your ears is just plain stupid. It's hard to put them on, and they don't stay formed enough to stay hooked over my ears. I have to constantly squeeze them together to keep them formed around the back of my ear. When I bought them I figured I would just not use that and use them like normal ear buds but if you do that the drivers are upside down and are out of phase therefore making them sound very strange. 
 
DO NOT buy these. They are horrid. I took the gamble on them so you don't have to. 

Ok where to start... I picked these up on sale for 20 bucks. I expected a bit from them since Skullcandy says they are worth $69.99. Let me tell you they are absolutely not worth that.... The monoprice 8320's sound much better than these so imho they are worth about 5 bucks. 
 
The bass is distorted and boomy. It overpowers everything and it is not clean at all. You can't even hear drum beats... All you hear is a boom where a nice solid tight drum hit should be. This ruins any clarity that you would be able to hear in any song. 
 
The mids are non existent. They just aren't there. They sound like if you were to do the typical V pattern on a graphic EQ to drop out all the mids. 
 
The highs are harsh and brittle. They completely ruin acoustic guitar songs and they make cymbal crashes painful.
 
I tried listening to every kind of music with these and I didn't find one that they sounded good for. These are just plain junk. About as bad as it gets sadly. 

A buddy of mine found a pair of these at microcenter for $30 on a crazy close out deal. The retail for these is $250. I borrowed them from him to test them out and give them a review and all I can say is they weren't even worth the 30 bucks. 
 
The first fundamental problem with these is they have an amplifier built in. That's great but it's not clean at all. You can hear the distortion it causes in the bass when you turn it on. You can also hear the bass rattle the plastic in the headphones on some tracks. The headphones have pass through but with the amplifier off the bass is gone completely, so in order to get these to sound anything like a headphone you have to have the amp on. 
 
The Bass:
 
Completely overbearing and muddy. Distorted to an extreme in some situations by the amplifier.
 
The Mids:
 
The mids on these headphones seem crushed down. They don't flow throughout the full sound of the headphone and it sounds as if they are trying to condense them for the bass. You get bass where you should get mids on the bottom side and you get nothing on the top side. 
 
The Highs:
 
The highs are rolled in to the mids at a fairly low frequency and are gone on top. There is nothing going on in the higher frequency ranges. They just cannot hit them. Acoustic guitar and voices suffer greatly from this and the clarity does as well. 

I had this card for a while and it did a decent job powering my AKG K550's and my Ultrasone 650Pros. I could always tell there was more to be had from them though. The sound was good but a tad muddy on the bass end and a tad clipped on the high end. 
 
After 6 months I got static output from the front panel and had to unplug it. After 10 months of ownership the card would output high pitched hissing noises at all times through headphones or speakers. 
 
I cannot recommend this card with the time it lasted me
 
Replaced it with a Creative Sound Blaster Z and I am highly impressed with how much better it is. 

I got this sound card to replace my Asus Xonar DG which died on me. The difference in sound quality between this card and the Asus is quite noticeable. Much more clarity and crispness in the high end. Bass seems punchier and more detailed. Power output seems like it is much better as well as I don't have to turn my headphones up as much as before. 
 
The software that comes with it is great. I love the ability to switch between speakers and headphones with the click of a button. No unplugging. I am also a avid PC gamer and the scout mode for video games really does what it says. It does a great job at making game sounds more defined and pulling in footsteps and enemy gunfire from farther away. The software does have a few features that should be avoided like Bass enhancement and crystalizer.... They just ruin the sound of a good pair of headphones. 
 
Overall I am highly impressed with this sound card and I can say it is light years ahead of the Xonar DG I had before and much much better than the Creative XtremeMusic I replaced with the Asus card. 
 
Install was easy on windows 7 and just as easy when I upgraded to windows 8 and did a clean install. No bugs, no crashes no driver issues. 
 
Creative hit a home run with this one!!!!