Sennheiser IE 900 Review

Sennheiser IE 900 Review

15 October 2021 0 By Petros Laskis

Sennheiser IE 900 Review

Pros: – Very musical and engaging
– Realistic timbre and lifelike tonality
– Excellent, reference quality bass
– Sub – bass extension and dynamics
– Holographic and wide soundstage
– Highly resolving but not analytical
– Discrete, lightweight and comfortable
– Great build quality
– Three cables with different plugs
– Quality hard carrying case

Cons: – Slightly lacking in scale
– Treble can be a touch hot but not bright
– Cable is a little microphonic and smelly
– Limited selection of ear tips.
– May not fit well larger ears
– You may need larger sized ear tips than the included
– Custom design MMCX+ connectors will not fit after market cables

The Sennheiser IE 900 was kindly loaned to me by their Greek distributor and is now returned back.

I am going to skip the usual introduction and technical information that can be found in the Sennheiser website.

Sennheiser IE 900

Build quality and appearance

The Sennheiser IE 900 is the first product to be released after Sennheiser consumer division was acquired by Sonova.
It is 100% handmade in Germany with top craftsmanship and excellent finish quality.
Aluminum is the only material used and a five-axis CNC machine precision cuts each housing individually from a single block of aluminum.
I have been reading about a handful of units with some assembly problems, mainly some kind of gluing issues at the plugs or something like that, but this wasn’t the case with the review sample which was perfectly assembled and finished.
The IE900 is beautiful looking with a minimal design reminiscent of modern cut jewelry.

Fit and isolation

The earpieces are so small and lightweight that they literally vanish in the ear to the point that you forget if you are wearing them.
The fit is very comfortable, relaxing and discreet with the only footnote concerning the fact that you may need ear tips larger in size than those included in the package.
Some people with deeper, than average, ear cavities may encounter some issues getting the proper fit due to the shell shape and the short length of the nozzle, so getting deeper insertion might be a problem.
Sennheiser should have included larger and double flange ear tips to better suit individual needs
Choosing the right size ear tips is of vital importance since if for some reason you do not achieve the perfect fit then the low end just disappears.
I have achieved the best results with the supplied memory foam ear tips.

Sennheiser IE 900


The detachable cable is of good quality, reinforced with para-aramid for better durability and it offers a great handling experience although it is prone to microphonic noise and the material is a little smelly.
The IE900 is worn around the ear and the cable features, the now out of fashion, memory bend ear hooks that offer a secure fit but are a little cumbersome.
Sennheiser, instead of designing a modular plug cable they opted to include three different cables with 3.5mm, 2.5mm and 4.4mm jacks to cover all types of plugs.
This is a little bothersome if you frequently switch sources but then, three cables are better than one in the long run.
Sennheiser uses Gold-plated Fidelity (+) MMCX connectors for improved stability and durability but while the supplied cables are of good quality, users who love cable rolling will have some trouble finding aftermarket options.


The Sennheiser IE 900 comes with three different cables, three pairs of silicone ear tips and three pairs of memory foam ear tips (arranged in a nice plastic shorting card), a hard carrying case of high quality and a cleaning cloth.
I perfectly understand Sennheiser not including fine tuning ear tips because the IE 900 tuning was done with the included ones in mind, but then they should definitely have included a couple of large sizes and some kind of double flange ear tips.


Listening set-up

As per usual practice the Sennheiser IE 900 was left burning for about 150 hours prior to critical listening.
The acoustic evaluation was done with various sources but for the main portion I have used the iBasso DX320 and the FiiO M11 Plus ESS.


Sound impressions

After testing dozens of iems with large, bass shaking, dynamic drivers in single and hybrid configurations, the truth is that I looked at the tiny 7mm IE 900 drivers with half an eye and some kind of distrust.
I have already reviewed the Sennheiser IE 300 featuring the same size drivers and I wasn’t disappointed but come on, a flagship with 7mm drivers when the competition comes with huge 12mm ones?
Being skeptical and slightly biased, I started the listening tests with bass stretching material to discover in my greatest surprise that the Sennheiser IE 900 passed all the tests with flying colors, not only offering a state of the art performance but it also outperformed most of the competition.
The quantity and quality of the low – end is just amazing to the point that one wonders how it is possible for such a small unit to produce that big sound.
Bass sounds full, visceral and weighty, deeply extending into the lower notes without rolling off, offering great sub – bass rumble, a versatile performer that feels at home from classical to bass boosted electronic music.
The tuning is balanced with a touch of warmness and the bass doesn’t cloud or mask the rest of the frequencies, moreover it is exemplary layered with perfect separation between the various instruments of the bass line.
Quantity is delivered in spades but not at the expense of the quality characteristics as it is tight, controlled and crystal clear with large impact and a grand scale in dynamic contrast that is unbelievable even without considering the size of the driver.
The continuation of the auditions revealed without any doubt that I was dealing with an iem of the highest level where technical performance was top notch and addressed at birth, allowing the designer to concentrate all his efforts and know-how in manufacturing a musical communicating instrument rather than the average transducer.
With the Sennheiser IE 900, fidelity and transparency are a “de facto” and not worth analyzing any further so we can discuss in depth about the timbre and tone of the sound.
Here the classical sound analysis into bass – mids – treble is vague and rather unnecessary since the timbre flirts intensely with the ideal, with the tonality of all instruments and voices touching reality not only in their harmonic wealth but also in their textural quality.
The Sennheiser IE 900 is particularly resolving and finely articulated without being analytical at all, standing out by the ability to offer a deep gaze into the recording venue and masterfully communicate the inner space and time domain, virtually teleporting the listener into it, making him a part and not a mere observer.
The stage extends beyond the ears and creates a deep, three-dimensional illusion with the performers occupying their desks with pinpoint accuracy and ample space between them.
If there is something to criticize is that the picture is missing in size and scale and there is the feeling that we are listening to the music like sitting in the balcony of the concert hall.
Sennheiser’s decision to stick with the time tested single dynamic driver principle paid off because the IE 900 sounds incredibly homogeneous, there are no phase shifts nor frequencies overlapping and the sound is coherent and solid.
The driver is fast and agile, the iem has excellent timing and fast transient response, a sense of inherent rhythm that can keep up when the music gets busy without losing its pace.
Percussion instruments fade away and decay with the most natural and shimmering reverb, not too fast nor too slow and above all without losing in body while reaching the higher frequencies.


At the end

Well, it is not a coincidence that Sennheiser is considered to be the leading headphone manufacturer in the industry and that seems to hold true even after the transition to Sonova.
The IE 900 is in my opinion, Sennheiser’s best creation after the legendary Orpheus and the iconic HD 650, it is more like a rare musical instrument of the highest rank committed to connecting the listener to the music.
Don’t let the size fool you as it did with me and make no mistake that the Sennheiser IE 900 is easily the best single DD iem on the planet and among the best of all kinds.

Test playlist

Copyright – Laskis Petros 2021