Still considering the 900 actually. I could eventually get both and return the loser. Just don’t want to abuse my annual returning quota, since the recent FH9 experiment was kind of a failure. 
This IEM game, I’ll be sure to play it on the long run.
Cheers. 
I did a writeup of it just this month actually. Of course take it w/ a grain of salt, but if you’re interested here’s the link: 900
Great write up.
I’m happy the 900 left a mark on you. Not sure about your game but my game for IEMs – as of today – is likely to be on the fun/aggressive sounding. Probably 10-15 minutes each session, tops. Adrenaline, not dopamine. 
And comfort, of course. It has been 10+ years using Shure IEMs for me. The small footprint and the MMCX connector make me have a big pair of 
at these Senns. 
For reference listening, I’d just pick one of the HD-6/800 Senn and be happy about it. 
Just got the IE300. They sound great, but they should be ashamed to include this kinky, proprietary recessed connection cable with a $200 product.
Just read your article, hits the point
I have a small recommendation for you that concerns the drive of the 900’s:
If you have the opportunity try it out, a fantastic symbiosis and an exceptionally good sound.
And looks:
Hifi headphone companies and bad cables, can’t name a better love story!
Thanks for reading! I did one when I first got it but I redid it after gaining more experience and spending more time with it. Things have definitely changed since then.
Thanks for the suggestions. But, oddly enough, I don’t use the 900 portably only at my desk. Though I’ll be sure to give those a whirl if I’m ever in the market for dongle DACs at some point. In return, I suggest you try them out with a quality tube amp (if you haven’t already). You might end up even more surprised.
I hear ya, but at least it’s better for longevity as there’s less stress on the delicate part of the connector.
I have been having some on the IE600/900 IEMs and a recent video from crinacle has opened some possibilities to try a “simulated” tuning of these two with SoundID Reference version 5 (Sonarworks for short).
I went to Super review measurements – e.g.: IE600, IE900, etc – and imported these measurements as target curves in Sonarworks. After some wizardly, of course. 
Then, voilà… my HD660S EQ’d towards the IE900:
AC/DC is crazy fun with the above tuning in an open back can. 
Alternatively, my SE846 EQ’d towards the IE600. Have to admit that this peak in the presence region is 
to my ears, although it can be aggressive in some tracks:
Hopefully the pictures are self explanatory. But in short: the black curve is the target – i.e., the modelled version of the measurement from Squiglink – and the green curve is the EQ being applied to the transducer by Sonarworks.
So what? The perks are:
IMHO, the Harman tuned IEM (Dusk – cough, cough) sounded boring and shouty when directly A/B’ing against the Senns presets. 
I am aware that there is a lot to be assumed though:
To conclude – how dare you? (meme) – these two IEMs look more like a W-shape to me than a U-shape signature. They somewhat remind me of the loudness button from those AIWA shelf stereos in the 90s. And I like it. 
Hopefully I can stay immune from the hype train a little longer. Curiosity kills sometimes though. 
Not a daily EQ’er myself but sometimes I like to experiment. Don’t shoot the messenger please. haha
Cheers.
Sennheiser IE600
The Sennheiser IE600 have been loaned to me directly by Sennheiser as part of a tour that was arranged on Head-Fi. The terms of the tour were that I would spend a maximum of 2 weeks with the IEMs, posting my honest opinions of them on Head-Fi at the end of the period. The also requested that any other reviews or comments on social media contain the hashtag #IE600Tour so they could be easily found.
There were a couple of other requests (such as at least trying the stock tips and comparing them to any other tips used, etc.) which you can find by visiting the first post of the Tour thread here: On the Road Again: Announcing the IE 600 Tour! | Headphone Reviews and Discussion - Head-Fi.org
No other requests have been made outside of the above thread, therefore, I will do my best to be as unbiased as I usually am, taking into consideration that it has not cost me anything to try out these IEMs.
Rather than sharing a specific official page link, I suggest you use this link: https://sennheiser.com/ which will take you to the relevant Sennheiser page for your location, from which you can navigate to the IE600.
Intro…
While I am someone who has been using Sennheiser gear for a very long time, due to me working in the pro audio field, I really haven’t had the chance to try any of their more hifi orientated IEMs. I have tried plenty of the consumer class stuff, along with plenty of their stage focused stuff, but the IE series is something that I just haven’t come across before.
I was very tempted to pick up the IE300 when they were released, to get a taste of what Sennheiser were doing with this line, but in the end I ended up not doing so. I was also interested in trying out the IE900, the TOTL in this series, but the price tag is something that doesn’t make it easy to blind buy.
So when the IE600 was released, priced at just under 600€, I was interested in finding out what they were all about and, when Sennheiser announced the tour, I was very happy to make the selection of people to get to try them.
Presentation…
The IE600 comes packaged in a very professional way. Upon opening the outer box, the two IEMs sit in a foam surround, which either makes the IEMs look tiny or the box look huge!
Beneath this top layer we find multiple documents, user manuals etc. and below these we get to the accessories.
The accessories included are 2 cables, one 3.5mm and the other 4.4mm, a square transport case, 3 sets of foam tips, 3 sets of silicone tips and a cleaning tool.
To be honest, the included accessories are what I would consider to be just the correct amount. There is nothing missing that we need to enjoy (and look after) the IEMs but at the same time, there is nothing included that is just to fill a void (except maybe for some of the packaging itself).
Balanced and unbalanced cable options are included, a nice travel case that is not overly large is included, basically offering a presentation that I would consider very well thought out.
Build and aesthetics…
Starting off with the IEMs, they are small and fairly lightweight (although they could be considered heavy for their size I guess). Completely made of what seems to be some kind of sandblasted metal, they look rugged and discreet at the same time. When wearing them, they are even more discreet, as they fit inside the ear very well, sitting flush inside the ear (at least in my ears).
Speaking of comfort, I find them to be probably the most comfortable IEMs that I have ever worn. Recently I said that the Airship were one of the most comfortable sets of IEMs that I had worn in a long time. Well, the IE600 came along and blew those out of the water as far as comfort.
Added to the comfort of the IEMs, there comes the cable. While I wouldn’t say the cable is anything special, it’s just a simple grey cable, the mouldable hooks over the ears are great. This reminds me of the moldable hooks on pro gear, such as DPA mics, that are made to be comfortable and not move throughout a show, no matter what the artist is doing. However, in the case of the IE600, these moldable hooks are covered with a slightly thicker outer sheath than the DPA mics (for example), making them work even better in my case.
When inserting the IEMs at the beginning, you do need to fiddle around a little to get the perfect fit, but once they are in place and the hooks are moulded to the correct shape, they are extremely comfortable (for me) and are going nowhere unless I want them to.
The cable itself is nothing special, as I already said, which sort of keeps up with the “pro” functionality of these IEMs. I would expect to just run the cable down the artists back, connect it to the belt pack, and not have to worry about it.
One thing that may be a negative for some is the fact that, while the cable does use MMCX connectors, they seem to be Sennheiser proprietary connectors. This means that you can’t just grab your favourite cable of choice and expect it to fit the IE600 (I believe this is the case with the IE300 and IE900 also). However, the connectors used are so smooth and so easy to connect/disconnect, without worrying about them being too loose or too tight, that it makes it almost worthwhile having to stick with the stock cable.
At the other end, while the 3.5mm/4.4mm is plastic, I have no doubt that it is also of great quality. I have Sennheiser cables that I have used thousands of times over the years and not once have I had to worry about the connector.
Another thing to point out, which I will discuss more in sound, is the included tips. These tips are also proprietary to the IE line of IEMs, as they include tuning material inside the actual tips. While I do know that some people have had issues with these tips, personally I find the included foam tips to be extremely comfortable and while I did try a few other tips, I also found that I preferred the sound with the foams.
The rest of the included accessories are of a quality that seems just as good and, while 600€ is not exactly cheap for a set of IEMs, I feel that the build of all of them are up to the standard of the price point.
Sound…
(Note: All tracks mentioned are clickable links that will open the track for reference in the streaming service of your choice)
As the IE600 is part of a tour (which goes back to Sennheiser between each person on the tour, for cleaning and replenishing with a new set of tips), I didn’t have to bother with putting it on the burn in rig for days to avoid the “it’s because you didn’t burn it in long enough” comments. So I opened the box, put them in my ears (marvelling at the comfort) and connected them to the Go Blu. Within 30 minutes, I had decided that these were the best single DD IEMs I have heard to date.
I have said many times in the past that I don’t put together any detailed impressions of things until I have been using them for at least 4 or 5 days as sometimes that period will either show more flaws that I hadn’t noticed upon first listen, or even get me used to the flaws and dfind that I enjoy them more than I originally thought.
During these two weeks, I haven’t used the IE600 exclusively as other things need to be reviewed, but I did find that, apart from the exclusive use for 4 or 5 days, that any time I felt like listening at other times of the day, I reached for the IE600. That is already something that goes to prove my very positive experience with these IEMs. They are not perfect, I will get into details in just a second, but I still feel that the overall sound of these IEMs is very very good.
I have to say that when I put them on the measuring rig, I was very surprised at the results. I do remember noticing that they had elevated bass on the graphs when I first saw measurements of them, but measuring them for myself brought me to realize that either:
a) I have become a bass-head without realizing it.
Or
b) These do not sound like they measure.
Before moving on and explaining what I mean, here is the graph of the IE600 with the usual foam tips I use for measuring, along with the included foam tips (the ones I have been using) and the included silicone tips:
As you can see, the low end is way above my usual preference target, but as I have said in the past, if an IEM is capable of producing very clean and articulate bass while still being boosted, I will often find that I like the low end. And that is the case with the IE600.
Starting off with the subbass, we are almost 10dB above my preference on paper. Yet to the ear, this subbass only comes into play when the song needs it. The IE600 don’t produce subbass on their own, they just boost what is already in the track and, as they do it in such a clean and articulate way, they come across as impressive with many subbass tracks.
Putting them through the usual “Chameleon” test, there is a large quantity of subbass but there really isn’t an overly present sensation of rumble, at least not to the extent I would expect looking at the graph. The same happens with Lorde’s “Royals”, although this track does have a subbass that is a bit more “out of control” than “Chameleon”, which is due to the recording more than the way that the IE600 portrays it.
The midbass is where I usually suffer when a set of IEMs is overly boosted in the low end. An overly present midbass is something that I find tiring and can make me want to either stop listening or move to music that has less of a bass presence. With the IE600 I did not get this feeling. Again, it is clearly boosted in these frequencies, yet somehow manages to keep the bass clean and stop it from interfering with the lower mids.
Listening to “No Sanctuary Here” by Marian Herzog feat. Chris Jones, there is no lack of bass presence to make this track sound excellent in the lower ranges, yet it does not detract from other parts of the song.
Moving away from more electronic bass focused tracks and towards bass guitars, here I did find on occasions that the low end was not quite as clean or tonally correct as I would like. For example, “Black Muse” by Prince, where this particular track did give me the sensation that the bass was overly bloated, missing some of the clarity that this needs to appreciate the bass playing. The same could be said for other tracks such as “No Ordinary Love”, where the music is much simpler, allowing the bass to become a little too present. As soon as I moved back to more electronically focused tracks, like “Shot Me Down”, the bass went straight back to being great.
What the IE600 does do is keep the bass away from the lower mids, offering a transition that is much cleaner than I would have expected from such a tuning. In fact, the mids on these IEMs are nothing short of excellent on most tracks.
Even more simple and melodic songs, such as “No Ordinary Love” that I already mentioned, or “Billie Jean” by The Civil Wars (to move more towards the acoustic side of things), sound very balanced and well defined throughout the mids. The upper mids have a rise around 2kHz which, while maybe not the best I have heard, do a very good job of presenting these voices and instruments with detail and not too much harshness.
Acapella tracks, such as “Hallelujah” or even “Happens To The Heart” (which is not exactly acapella but almost), do sound clear and articulate, although, in the case of Leonard Cohen, I got a sensation that it was maybe not quite as smooth as it could be.
After the 2kHz mark there is a bit of a dip which, thankfully, does not come back with a peak at the 5kHZ mark like on so many other sets. I do feel that the presence just above 2Hz could have extended slightly more, maybe to just past the 3kHz mark, but that is just a personal preference and more of a nit pick than anything else.
As we get into the higher ranges, there is a bit of a peak that can suddenly appear now and again, giving the sensation of a bit of brightness that can come across a little harsh, such as brief appearances in “Sugar” by Francesco Yates. Sibilance is mostly controlled, although not eliminated, making “Code Cool” be just hovering on that sibilance mark, without actually getting there.
As far as soundstage, I would say that it is not huge, maybe at the higher side of average, yet the image placement and details make it seem like there is much more space than there actually is. With tracks like “Bubbles”, you can focus on literally any of the sounds and follow them, without ever getting the sensation that you have lost them. The same can be said for “Strange Fruit”, where each and every layer of vocals can be tracked on its own.
Last but by no means least, the detail. The details that this small dynamic driver is capable of presenting is very impressive. I never found that I was having to focus on anything to appreciate the details, yet at the same time, it doesn’t push them in your face. It just does a very good job of keeping everything just where it needs to be.
Conclusion…
I haven’t mentioned it during the review as I always share my opinions without EQ, yet, I find that with a little bit of EQ, these IEMs go from being very good, to almost excellent. I found that dropping the low end quite a bit (not 10dB to match my target but around 6dB), along with just a little tweak of the upper mids (to extend that 2kHz presence just a little more) really opened up these IEMs and made them sound amazing (in my opinion of course). Now, I am in no way saying that my little tweaks improved these IEMs, far from it, more that they adjusted them to my personal preferences.
Without EQ, these are still very good IEMs, with a performance that I find spectacular for a single DD, providing details that are way above what I expected. I am sure that others, who prefer more bass than me, will enjoy the tuning as is.
I also feel that the build, aesthetics, cable, accessories, everything really, is well thought out and is presented in a way that I doubt anyone could fault.
In fact, with the possibilities of EQ, I wouldn’t hesitate to recommend these IEMs as on stage monitors to any of the artists that I work with. As each artist gets their own in-ear mix, the IE600 can be tailored to almost anyone, as there isn’t anything missing, just some people will prefer to drop certain frequencies more than others.
And then there is the comfort. If ever there was a set of IEMs that I would want in my ears for extended periods and just forget they are there, the IE600 are those IEMs.
(as always, this review is also available in Spanish both on www.achoreviews.com and on www.youtube.com/achoreviews)
All FR measurements of IEMs can be viewed and compared on achoreviews.squig.link
All isolation measurements of IEMs can be found on achoreviews.squig.link/isolation
Picked up a pair last week and they’re my first IEM I’ve owned (other than AirPods). I mostly listen to R&B, metal, synthwave, hip-hop, funk, jazz, and prog FWIW.
Tonality is great on these. Bass is pronounced without muddying anything and some songs rattle my brain a little (e.g. Price of Fame by Brent Faiyaz). Vocals and guitars all sound great to me and don’t sound veiled. And fortunately, I don’t experience any sibilance or too spicy treble. I was worried about this because I’ve found I’m very sensitive to treble and generally prefer dark headphones.
One con and I don’t know if this is exclusive to the IE600 or IEMs in general, but imaging does not exist. Compared to my 660s and LCD-5, the IE600 is one giant blob. Track that highlights this is Reflection by Tool. On the LCD-5, every piece of the drum kit is in a distinct place around your head; IE600, all drums are in front overlapping one another. I know this is an unfair comparison given the price disparity between the two transducers but felt it worth mentioning.
Because of the lack of imaging causing sounds to overlap and shrinks the soundstage. Intricacies in songs are much more difficult to pick out. E.g. reverb in most of my R&B library. In Pyramids by Frank Ocean in the 2nd verse after the beat drop there is reverb on his voice that can’t be discerned on the IE600.
This lack of imaging is me nitpicking because in reality this IEM sounds great and scratches my music itch when on the go.
Are you using crossfeed?
Can improve imaging and/soundstage.
I am not using crossfeed. I used crossfeed back when I owned an RME ADI-2 but after selling it I didn’t see a need to implement it in my desktop setup. Imaging really isn’t a deal breaker for me tbh just a critique I hadn’t seen any other reviewers mention.
And perhaps I’m spoiled with my LCD-5 and $2k in source equipment when comparing it to the IE600 and an Apple dongle.
If your lcd-5 source chain is fine to use with IEMs, I’d encourage trying it on the 600. You probably use it on the go but just try it as an experiment. Who knows, you might end up surprised.
I have a Ferrum Oor for my amp so all I need is a 1/4" to 3.5mm adapter. Guess I’ll order one and report back!
Shout out to my box of miscellaneous cables for containing a 1/4" to 3.5 mm adapter. Immediately upon hooking up the IE600 to my Oor + Bifrost 2 chain (which is what I use my LCD-5s with) and listening to Reflection by Tool, the imaging returned.
I like to have a healthy skepticism towards source equipment (despite being deeply invested in them haha) and view myself as right in the middle of the objectivist / subjectivist continuum. And not gonna lie, this finding has my objectivist side a little shaken. Imaging is a binary trait to personal audio (i.e. it’s either there or it isn’t) and I did not expect source equipment to have such an impact on it.
Well I’m glad it led to a positive new discovery. I use an ie900 on my desktop chain for the reason of it being able to scale really well.
Just a thought, if you think your oor is best using balanced, it might also benefit your ie600.
One thing I learned in this hobby is you never really know until you try and plug it in. It’s a simple thing, yet often forgotten.
A collection in which the individual character of each model immediately catches the eye/ear.
Paired with the most compatible amp partner in terms of sound, Sennheiser offers an extraordinary sound quality and variety, with a “simplicity”, at least seen from the optics and driver type.
But which works well above average.
All three models, seen for themselves, have exceptionally good properties that can lead to a certain “addictive behavior”.
Is any of these the better in-ear?
No, because they sound and “feel” completely different.
Which, depending on the mood and music genre, can (do not have to) be state of the art.
Just picked up a pair of Sennheiser IE 600 iems, after reading many positive reviews. In addition to the reviews I got them because they are light and small - I can forget that they are in my ears, which suits a number of listening situations for me. I can even lie on my side with them in. I also feel that they are a good value for the money.
The bass is surprising from these tiny earpieces.
I have been A/B’ing them with my 64 Audio U12t iems. Of course these IE600s are not as suitable for critical listening, with more of U-shaped FR presentation, less balanced, and the sound stage is about a foot wide. But I find the timbre to be pretty accurate.
In short, I find these Sennheiser IE600s quite enjoyable (with a little EQ to tame the bass and slightly bring down the 8k peak for a more balanced tuning IMO). I am using Azla Sedna Crystal tips which work quite well and are super-comfortable. I am using the balanced 4.4 Pentacon cable provided, and glad that they supplied a separate cable. At this point, I doubt that I will invest in a better cable.
I have to agree. I didn’t realize how much comfort affected my perception of iems, but the ie600s “disappear” so I can concentrate on the music and not be aware of “something in my ear” distraction.
I generally don’t like moldable hooks, as they are too stiff, but these are flexible and comfy
This is also my experience. This is an iem that i reach for instinctively, although I have a TOTL iem available. I guess the combination of comfort and reasonable sound quality is the reason.
I really appreciated your review, as it mirrors my experience. When I first tried the ie600s the bass was overwhelming. I did tame the bass with EQ to get there. In my mind, these IEMs punch above their price with a bit of parametric EQ.
+1 I really like them, probably because they are the lightest and most comfortable IEMs I have owned. A great combination of performance at a price that is not stratospheric.
