Note: This review was first published on 19 August 2021 and it's republished now because it's still Sennheiser's flagship IEM and is still one of the best-sounding IEMs you can buy.
The IE 900 are Sennheiser's newest flagship IEMs.
Behold the new flagship
Unlike phones, flagship IEMs don’t come around often. Sennheiser’s last flagship-class IEM, the IE 800 S, was released in 2017. So you can imagine the excitement the new IE 900 caused when it was announced earlier this year in May. The move is a concerted effort by Sennheiser to refresh its IEM lineup which started in January this year with the IE 300. On paper, the two have a lot in common, but as we all know, specs barely tell half the story especially when it concerns audio.
Design & features
Build quality is peerless. The milled aluminium shell feels solid and indestructible.
The IE 900 and IE 300 share the same design which is no bad thing. The IE 300 was supremely comfortable to wear and the IE 900 is no different. Its fits snugly in my ears. And because it’s so small and light – a mere 4g – you barely notice it in your ears.
The main differences lie in where they are made and the materials. While the IE 300 is made in China, the IE 900 is made in Germany. It’s an important point of distinction, especially for enthusiasts, mainly because it costs S$1,999 and also because only Sennheiser’s most important and premium products are made in their German factories.
Crafted directly into the aluminium shells are these resonators that tame high frequencies. (Image source: Sennheiser)
On the materials side of things, while the IE 300 makes do with a hard plastic shell, the IE 900 features a milled aluminium housing. Each IE 900 shell starts off as a block of aluminium which is then precision-milled to create its unique shape. This step is particularly crucial because within the aluminium shells are three Helmholtz resonator chambers that were designed to minimise unwanted frequency peaks.
The shell feels bombproof. Milling leaves tell-tale lines and Sennheiser decided to embrace this by accentuating the milled lines on the shell. The final result, to my eyes at least, is quite aesthetically pleasing. The shells are also anodised so that they are resistant to wear and corrosion.
The bundled cables are sturdy but they also feel stiff and rubbery.
The IE 900 uses MMCX connectors. The connectors are specially designed so that they sit within a recessed socket so that there’s strain relief. This might causes compatibility problems with aftermarket cables so pay attention to fit if you intend to use your custom cables with the IE 900. Bundled with the earphones are three cables with 3.5mm, 2.5mm, and 4.4mm plugs so that owners can use their IE 900s with a wide range of balanced and unbalanced devices. These cables are made of para-aramid which Sennheiser says can withstand “many thousands of bend cycles”.
Sennheiser should be applauded for providing this many cables and the cables certainly feel strong and durable. However, they are also quite stiff. And this, coupled with the fact that they are coated in a TPU material, make them feel like rubber hoses. So as high quality as they may be, they don’t feel quite feel like premium items. The current trend is for high-end IEMs to come with braided Litz cables which are often soft and pliant and Sennheiser could definitely look to emulate that.
The IE 900 comes with six additional pairs of silicone and memory foam ear tips.
Included with the additional cables are six additional pairs of ear tips – three pairs of memory foam ear tips and three pairs of silicone ear tips. The silicone ear tips feel smooth and soft but my preference is for the memory foam ones. They do a noticeably better job at blocking out unwanted ambient noise. Owners also get a sturdy carrying case that is emblazoned with the serial number of the earphones and has sufficient space for the IE 900 themselves and all the additional cables.
Audio performance
The IE 900 features a 7mm TrueResponse dynamic driver.
Unlike other companies that differentiate their earphones by using drastically different drivers, Sennheiser prefers using variations of the same driver across its lineup. Therefore, inside the IE 900 is a 7mm TrueResponse dynamic driver that’s closely related to the driver that is found inside the IE 300.
When quizzed, Sennheiser’s response was that the 7mm TrueResponse driver was developed to be as good as it can be and so it makes sense for them to use it across their various product offerings. And while the driver may be similar, the tuning treatment most definitely isn’t. In the case of the IE 900, greater care has been taken to tune the driver to maximise its performance. They point toward the three precision-milled Helmholtz resonators as an example – something that the IE 300 lacks. Greater attention has also been paid to managing airflow and backpressure in the IE 900 as evidenced by the more prominent vents.
Tiny vents help control air flow and back pressure in the IE 900.
Some readers might also wonder why Sennheiser opted for a single dynamic driver setup, which is a rarity in the world of ultra-high-end IEMs dominated by multi-driver configurations. The reason, explains Sennheiser, is that while multi-driver configurations might achieve better frequency response, they do so by sacrificing timbre, coherence, and phase performance. Put simply, it’s a challenge to get all the drivers to sound like one cogent unit. In Sennheiser’s books, it’s preferable to have a single very high-performance driver.
But the fact is that phase coherence and timbre are unlikely things that most audiophiles would notice unless the IEM in question was tuned horribly. Still, the IE 900 has a naturalness and coherence to its sound that is refreshing in this rarefied space of über high-end IEMs.
The provided carrying case offers good protection and has a plaque with the earphones' serial number.
Tonally, the IE 900 sounds mostly even. Bass response is tastefully elevated, and crucially it is tight and punchy. But it is the treble extension that really gets you because it’s so well extended and smooth. There’s no harshness or sibilance, just lots of air and sparkle. The problematic area for me is the mid to upper mids, there’s some unevenness there so vocals sound breathier and more hollow than they should.
Technically, the IE 900 is quite resolving and detailed but perhaps not quite to the standard one might expect from a summit-fi IEM. I attribute this to the unevenness in the mids to upper mids. The breathier vocals can sound indistinct as a result and some instruments like pianos and guitars do not sound quite as incisive. Imaging is solid and the stage that it projects is slightly wider than average, which makes well-recorded live recordings a treat.
IE 900 vs IE 300
The IE 300's V-shaped tuning is more fun and consumer-friendly.
Against the much more affordable IE 300 (S$449), it is clear that the IE 900 has a more balanced sound. Its tuning is also more refined and more in tune with what audiophiles are looking for. The IE 900 also has more resolving power and sounds appreciably more detailed and clean. That’s not to say the IE 300 is bad. For a fraction of the price, the IE 300 acquits itself well but there’s no denying that it has a more consumer-friendly tuning that’s more U-shaped with greater bass and treble emphasis. There’s no question that the IE 300 is the more rambunctious and fun-sounding IEM and there’s nothing wrong with that.
IE 900 vs Sony IER-Z1R
The Sony IER-Z1R is a worthy if considerably more expensive alternative to the IE 900.
If you are looking for a high-end IEM from a big name brand then the obvious alternative is Sony’s IER-Z1R. At S$2,499, it’s even dearer than the IE 900. And unlike the IE 900, the IER-Z1R uses a multi-driver setup that consists of two dynamic drivers (one 5mm, another 12mm) and a balanced armature driver. Tonally, the IER-Z1R sounds more even and correct to my ears. Sub-bass is superb and there’s less unevenness in the mids compared to the IE 900 so vocals sound more natural and livelier. The Sonys sound better.
However, the Sonys have one glaring flaw and that is their weight. The shells are made of zirconium and they are heavy. While the IE 900 weighs a mere 4g, the IER-Z1R are a whopping 26g. The difference is immediately apparent. And no matter how good they sound, an hour was the maximum I could go before feeling pain in my ears. Of course, your mileage may vary but this is a common complaint of IER-Z1R owners.
The choice for sensible audiophiles
The IE 900 may not be the best-sounding IEMs but as a package, it's very well-thought-out and complete.
Judged solely by the way it sounds, the IE 900 is competitive but not class-leading. Where it really outshines its competition is with its superlative build and compact design. It feels bombproof. And because it is so small, it's supremely comfortable to wear. This addresses a common issue with high-end multi-driver IEMs – many are too big and torturous to wear for any extended amount of time.
So when taken as a whole, the IE 900 becomes a much more appealing package. It sounds respectable for a summit-fi IEM, it's built to very high standards, comes with all the accessories one might need, and is more comfortable to wear than most, if not all, of its rivals. Ultimately, like most other German-made products, it’s practical and sensible – as sensible as S$2,199 IEMs can be. I think the people who buy it will be very satisfied with their purchase.
Note: You can find the Sennheiser IE 900 on Amazon, Lazada, and Shopee.
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