This article uses affiliate links, which means if you purchase products through these links, we may earn a commission. Click here to see our T&C. For licensing please click here.
Hands-on with the Sennheiser IE 900
Hands-on with the Sennheiser IE 900 IBTimes / Jeff Li

After testing the new Sennheiser IE 300, we were very impressed with the quality sound that can come out of such a small earbud that used only a single dynamic driver. However, only weeks later, we were pleasantly surprised by the announcement of the IE 900 that we perceived as a high-end version of the IE 300.

Though the shape of the Sennheiser IE 900 looked quite similar to it's counterpart, telling from the price point we're guessing there's more than meets the eye. Let's dive in to find out what the new Sennheiser flagship IEM holds.


Precision Milled Aluminum IEM Shell

From the get go, the veteran German audio electronics impresses with the IE 900's unique aesthetics. Using a machined shell is nothing new with IEMs, but the precision-milled and anodized aluminum shell has a unique raw - yet refined look.


From afar, they simply look like polished aluminum, however up close, the design team decided to leave the machining marks from the CNC mill in the body contour instead of polishing them out. The result is an iconic finish wrapping around the new Sennheiser IEM profile.


Just like the IE 300, the small footprint of the IE 900 earbuds makes them very lightweight - like a natural termination of the cords, which wraps itself around the ear nicely. The fit in the ear is secure and comfortable, together with the durable unibody aluminum shell, these are earphones that have all boxes ticked of becoming your everyday carry (EDC) earphones.


Hand-assembled at Sennheiser HQ

Though the Sennheiser has the industrial look of something made in the masses using computerized assembly lines - the truth is quite the opposite. Each of the IE 900 earphones are hand assembled in the Sennheiser headquarters at Wennebostel, Germany, a point of difference from its sibling the IE 300. This is why with the IE 900, you get a hand-signed certificate of authenticity from the quality control operator, containing the serial number as well as the manufactured date stamp. The serial number is also etched on a metal plate on the bottom of the carrying case, ensuring that your earphones retain their unique identifier.


According to the statement on the certificate, each transducer and earphone are hand-selected and paired up, making the IE 900 more like a custom hand-built earphone than a mass-produced one.


Even more Realistic, Detailed Sound

So what does all the 'hand-building' amount to in terms of the actual listening experience? Using the included balanced cables to get the best possible sound out of the IE 900, I tested it with the latest FiiO M11 Plus LTD DAP, and I have to say that the result is glorious. Without a doubt, these are one of - if not the best sounding In-ear Monitors I have heard.

Although the IE 300 was already impressive in terms of its detailed highs and nuanced low-end, the IE 900 ups the ante when it comes to the 'thickness' of the sound, providing more to 'bite into'. With these flagship IEMs I'm getting the vibes of really high end headphones when it comes to how realistic each instrument sounds coming out of them.

The secret of the realistic sound presentation seems to come from the new triple Helmholtz resonance chambers that are now built into the transducer. Coined by Sennheiser as the X3R, the idea is for resonance to be tuned using the shaped chambers within the encased transducer. Much like creating a different sound through blowing over different sized bottles, these internal chambers tune the IE 900 sound to perfection.


Huge Soundstage in a Closed-back

Even though the IE 900 are closed-back earphones, the huge soundstage made me doubt a couple of times that it must actually be open-backs. I confirmed what it is through turning the music volume up, and putting a finger onto the sound exhaust, and found that indeed there is zero sound leakage.

This means you're able to enjoy the realism and staging of the open-backs while not needing either huge cumbersome cans, nor needing a secluded place where sound leakage will become a problem.


Superior Instrument Separation from a Single Transducer

The new transducer technology from Sennheiser is more than the diaphragm, but seems to be in the case design around the transducer. Other than the aforementioned resonance chambers, there are also separate chambers that control the sound through controlling the volume of air. It's interesting that even though the IEM 900 transducer uses a more traditional dynamic driver technology, the whole thing is encased - almost like a balanced armature, giving it superior control.

I tested the IE 900 with one of the most complex pieces of music that I know: the Original Motion Picture Soundtrack of TENET composed by Ludwig Goransson. By using 24bit FLAC files, I ensured that I'm using the cleanest, most unadulterated source, and it sounded incredible. The IE 900 captures each of the textures of the mixture of synthetic and acoustic sounds, presenting each sound individually while mixing them in its wide soundstage.

This impressive feat was confirmed when I did A-B testing of the tracks with the UE CSX 11, which is a champion in its own right in terms of reproducing details in music. I found that the two premium earphones are on par in terms of producing each minute element in the track, the IE 900 sound is superior when it comes to realism, especially when it comes to acoustic instruments. So just as I recommended the CSX 11 for electronically amplified music, I recommend the IE 900 for unplugged, acoustic music.


Balanced Cables Inside

Matching the premium performance of the IE 900 earphones, Sennheiser includes three individual cables in its package: a normal 3.5 mm jack, a 2.5 mm TRRS balanced jack and a 4.4 mm TRRRS balanced jack. This allows the user to tap into the best, cleanest output from the IE 900 with improved performance in soundstaging and separation without needing to look at aftermarket cables.


Final Verdict

The Sennheiser IE 900 presents the German audio electronics company's latest and greatest, and we were very impressed. From the design, build, sound quality and even accessories, you're looking at a product that will offer you the best listening experience when you're on the move.


It's durability means you're able to enjoy it on a daily basis, and its closed-back design means you can enjoy these in whatever environment you're in. We are awarding the IE 900 as one of the best EDC earphones money can buy on the market.

Sam is a production engineer turned tech writer who specializes in seeking out gadgets that enhances productivity while still looking sharp. This is a contribution to an ongoing IBTimes review series on EDC tech gadgets.