Sennheiser IE 900 Review - Flagship Dynamic Driver IEM

Written by Chrono


Over the last couple months and starting with the IE300, Sennheiser has begun to slowly get back into the IEM game with new products, or refresh of prior ones. What we’ll be taking a look at in this review, then, is the brand new and very exciting Sennheiser IE 900, which was designed to serve as Sennheiser’s in-ear flagship headphone and to deliver an uncompromised listening experience regardless of where you are, and where you go.

Of note, the Sennheiser IE 900 is not yet up for purchase, but it will become available starting in June for $1,299.95.

Sources and Music Used in Listening Tests

All the listening for this review was done on the Astell & Kern SR25. For the listening tests I used music from a wide variety of genres including Rock, Jazz, Classical, Acoustic, Hip-Hop, and latin. I played tracks from my own FLAC library as well as from Tidal Streaming Service (Master Quality).

Sennheiser IE 900 Review |


Despite its exterior packaging being identical to that of the Sennheiser IE 300, the unboxing experience once you get past the outer sleeve is completely different. Inside, you’ll find a box with a pull out tab, which contains the Sennheiser IE 900 as well as all its documentation and accessories. 

For starters, you are greeted with a certificate of authenticity, which has the headphone’s serial number, and a signature from QC inspection. Then, there is a tray with six different sets of tips, which--like on the IE300--are three pairs of silicone tips, and three pairs of foam tips. Additionally, there are three cables included, and whilst they all use semi-recessed mmcx connectors for the headphone side, they have varying terminations. One is a standard, single-ended 3.5mm cable, another one is 4.4mm balanced, and the last one is 2.5mm balanced; which gives you some flexibility for connectivity. 

Last but not least, the IE900 includes a Sennheiser cleaning tool and microfiber cloth, as well as a very portable, low profile case that features a plaque with the headphone’s serial number at the bottom. 

Build and Comfort

The IE900 features the same compact, and ergonomic design featured on the IE300, and on Sennheiser’s Pro-series IEMs. The only difference here is that the IE900 is milled from a single block of aluminum and has grooves that texture the chassis. Despite the metal housing, though, the IE900 remains pretty lightweight and easily portable. 

For comfort, the IE900 is truly outstanding. The small chassis makes for an IEM that I don’t think many users will have issues getting a good fit with, so they’re definitely friendly towards users whose ears are on the smaller side. Now, the tips themselves are identical to those on the IE300, so I may sound a bit repetitive when describing them. Like  on the IE300, I really like the foam tips that are included with the IE900, they’re easy to work with and they work wonders in getting a good, consistent seal that also provides solid noise isolation. On the other hand, I’m still not particularly enthusiastic about the silicone tips included, as I wasn’t able to get a proper seal with any of them, which really hurt the tonality of the headphone. Naturally this will vary greatly from user to user since our ears are shaped differently, so these tips may not be an issue for you, though I still wanted to share my experience with them. 

Sennheiser IE 900 Review |


The IE900, like Sennheiser’s other IEMs, is utilizing a single-dynamic driver. Though, what Sennheiser has done for the IE900 is that they’ve implemented their new X3R transducer,  combining their refined 7mm Extra Wide Band Transducer with a triple-chamber absorber system. So, with its cutting-edge design, how does the IE900 perform?

First Impressions

Well, I know I’ve given some of my thoughts away in the “First Look” video I made for the IE900, but to briefly recap, I think it sounds rather good. In fact, it’s probably the most enjoyable listening experience I’ve personally had in an IEM thus far. It’s not without its flaws, of course, but it’s got a very nice presentation that is surprisingly spacious, with a good tonality, and even great dynamics. Whilst I will say that it immediately struck me as having a slightly bright frequency response, it wasn’t offensive or harsh, and it actually had a very good midrange and low-end response. 


Admittedly there haven’t been many (yet!), but of the IEMs I’ve had the opportunity to listen to, the IE900 has my favorite bass response. It’s got a very generous bass shelf under 120hz, which gives the subass region a lot of presence, energy as well as a deep rumble. However, it’s not overbearing over other frequencies, and instead feels both enjoyable and clean. It’s perhaps a bit more elevated than what I would personally consider to be “neutral-sounding,” but it makes for a bass region that is fun, and the IE900 is undoubtedly very capable at keeping its bass reproduction tight and controlled. Additionally, it is worth noting that like on other IEMs using a dynamic driver, the bass is punchy and has some satisfying kick to it. 


The midrange on the IE900 is one that I think is accurate, with a tonality and balance that reminds me of the HD800S, and the HD 560S; two headphones of which midranges I’m fond of. Throughout, the mids are linear with an organic voicing that keeps the fundamentals of vocal and instrument lines natural-sounding. Occasionally I felt as though the IE900 was just a little forward at around 3.5K when compared to my Vérité Closed, or even to my HD600, but I’m fairly sensitive to the upper midrange, so I think that for most listeners it won’t be an issue. Regardless, it’s a great depiction of the midrange; brass instruments carry their energetic bite, and electric guitars have their distinct buzz and growl. 


The treble range is where I think that some listeners might have some trouble with the IE900. As I mentioned earlier, the highs do have a bit added brightness to them. In the lower-to mid treble, it sounded to me as though there was fairly broad elevation centered around 6K or about maybe 4-5dB. This, in combination with a narrower peak at around 8.5K, I felt really highlighted the overtones and harmonics in that region which made for a treble range that did sound ever so slightly unnatural in its brilliance, and it did also introduce some sibilance. Again, this didn’t make the IE900 harsh or piercing in the way that “peaky” headphones such as the DT 1990 Pro are, but over extended listening sessions it could become a little bit fatiguing or distracting. 

This elevation aside, I still think that the treble range on the IE900 is pretty good. Since the elevation is not narrow, it doesn’t stand out or make the highs feel particularly uneven. Additionally, I really appreciate the IE900’s excellent treble extension, as it has nice air qualities above 10K that properly nuance the glisten of vocals and the splash of cymbals. 


For its detail retrieval and overall sense of clarity, I found the IE900 to deliver very good performance. Even compared to the similarly-priced, balanced armature CFA Andromeda 2020, the IE900 to me seems to deliver a cleaner image of the music, with all vocal and instrument lines having a defined structure, and adequate texturing. 

Soundstage, Imaging, and Layering

The IE900 has truly outstanding spatial qualities, and I think that they may just be where it shines brightest. Since it’s an IEM that works with an extremely compact enclosure, no, it doesn't have the kind of soundstage that you’d get from an over-ear headphone. Still, it feels remarkably more open and spacious than other IEMs I've listened to, which makes for a listening experience that is nowhere near as confined as what you’d expect from an in-ear headphone. For imaging, it easily discerns the positioning and directionality of sound, revealing the location of sound cues accurately. Additionally, it’s got equally good image distinction and layering. Instrument lines retain their distinction even through busy musical passages, which I also think is something that strongly contributes to the IE900’s perceived clarity. 


As mentioned earlier, the IE900’s dynamic driver delivers engaging dynamics that heighten the musicality of the listening experience. Low tones are fast and punchy, whilst upper registers have a satisfying bite and defined attack. Overall, the IE900 provides a good sense of tactility that gives instruments a more realistic and energetic presence, and in this regard it’s among the better IEMs I’ve heard. So, if you’re looking for an IEM with a good sense of punch and slam, I think you’ll enjoy the IE900.

Sennheiser IE 900 Review |


The slightly emphasized treble region may be a bit of a put-off for some listeners, but as a whole I think the IE900 is a very good IEM. It’s one that I’ve personally really enjoyed listening to, as it’s got excellent technical performance, a good tonal balance, and great comfort--undoubtedly a well-rounded headphone that I’d gladly recommend.

One more thing I should note, is that in a high-end market that’s continuously steering towards multi-driver and hybrid solutions, the IE900 is an outstanding option for listeners who really enjoy the kind of presentation that a single dynamic driver has. If this is something that, like me, you value in your listening experience, then you may want to keep this one on your shortlist. 


Watch the video review here:


Discuss the Sennheiser IE 900 on the HEADPHONE Community Forum.


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