Headphone and Earphone Reviews

Sennheiser IE 900 IEM Review.

The IEM (in-ear-monitor) market is hot. When I was at CanJam SoCal 2023, a lot of the floor was taken up by IEM vendors.

The design and complexity of many of these IEMs reflected the race for the newest designs, many with a combination of driver types, and crossover technology. The most common of those drivers are dynamic, balanced armature, electrostatic, bone conduction, and planar magnetic. And then, there is Sennheiser, whose flagship IEM has a single 7mm dynamic driver. At CanJam there was only one IEM that made me smile and want to listen to it at greater length, and that was the Sennheiser IE 900.

The Sennheiser IE 900 is a tiny precision-manufactured, anodized aluminum IEM that looks like an art deco sculpture because Sennheiser chose to leave the lathe marks that accentuate the organic curving form. They stand in simple, elegant contrast to the sometimes-gaudy over-the-top bling so ubiquitous to the IEM market today. Each pair is precision cut from a single block of aluminum on a 5-axis CNC (computer numerical control) machine and then hand-assembled by a team of specialists at their facility in Ireland. This is the same plant that produces their electrostatic HE 1, HD 800S, HD 650, and HD 600 headphones. The milling process alone takes 40 minutes, which includes the precision carving of three resonance chambers, and an acoustic vortex chamber, each a different size and shape. The final stage is to anodize the aluminum.

Highlights

Sennheiser IE 900 IEM Highlights

Single dynamic 7mm driver provides precise detail and impressive bass.
X3R transducer system.
German engineering at its best.
Anodized aluminum housing.
3 Helmholtz resonator chambers for shaping the high frequencies and revealing minute details in the music.
Small and lightweight, comfortable for hours of listening.
Excellent noise isolation.
Comes with a selection of both silicone and memory foam ear tips in small, medium, and large.
Three para-aramid reinforced cables with balanced 4.4 and 2.5mm and unbalanced 3.5mm jacks.
Adjustable, bendable ear hooks.
Gold-plated MMCX connectors.
Impressively wide soundstage.
Warm, natural presentation.

Introduction

This July marks one year since I was invited, as a fledging audiophile, to join the team at Secrets. My education in learning the technology of headphones, cables, and amplifiers continues to be one of the delights of my audio life. My passion for headphones was limited to the narrow range of headphones that I had owned. In one year, I have had the privilege of spending quality time with some of the most highly regarded headphones in the head-fi world.

My experience with IEMs consisted of my Apple AirPods Pro, and my beat-up Bose sports buds I wore while hiking. That changed when I attended CanJam SoCal 2023.

At CanJam I was surrounded by a tsunami of IEMs. I listened to or learned about at least 20-30 different companies’ offerings. By the end of the first day, my brain was full, and my ears were numb. On a whim, I stopped by the Sennheiser booth, which was on my list for the next day. When I tried out the IE 900 my brain cleared, and I forgot about my fatigue. The first thing I noticed was how much easier they were to fit into my ears; a major problem I had with other IEMs. I have small canal openings, and as a result, I haven’t been able to fully appreciate many IEMs as it is impossible to get a proper seal. The IE 900 are tiny and when properly seated in the ear, they nuzzle right into the canal and stay firmly seated.

One of the reasons I love over-ear headphones is the presentation of the music. In a good set of headphones, there is a spacious presentation and room for a decent soundstage and placement of the musical elements and voices. I haven’t found that to be as true in my experience with in-ear devices, which sound intimate and close; nice for general listening, but not what I pick up when I want to sit down and really listen to music. All that changed when I first listened to these at CanJam. My brain stopped for a moment when I played a selection of music from my phone. I think the first words I said were “I don’t have to give these back, do I?”. I had never heard bass presented in such rich detail in any other IEM. Quality bass can make or break a headphone for me; no matter how well presented the mids and highs are in a headphone, if the bass isn’t in proper balance the music will sound lacking in warmth and life. Unfortunately, the show was noisy and crowded and I couldn’t focus to listen more closely. I handed them back with a promise to myself to spend more time with them in a proper setting.

That time is now, and I get to spend some quality time with the IE 900 and put them through their paces.

Sennheiser IE 900 IEM Specifications

Transducer principle:

dynamic, Extra Wide Band (XWB)

Transducer size:

7 mm

Frequency response (speaker):

5 Hz-48,000 Hz

Ear coupling:

In-ear, closed

Sound pressure level (SPL):

123 dB (1 kHz, 1 Vrms)

Total harmonic distortion (THD):

Cable length:

1.25 m

Connector:

stereo jack plug, gold-plated, MMCX plug

Impedance:

18Ω

Attenuation:

-10 dB

Website:

https://www.sennheiser-hearing.com/en-US/p/ie-900/

Company:

Sennheiser

MSRP:

$1,199.95

SECRETS Tags:

Sennheiser, IE 900, IEM, In-Ear Monitor

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Design

The compact anodized aluminum housing contains the X3R transducer built around the “one driver” principle. Sennheiser feels that multi-driver systems introduce phase incoherence and unwanted distortion caused by overlapping frequency bands of the driver-crossover mechanism. The X3R system has three Helmholtz resonator chambers of different sizes precision-drilled into the chassis between the diaphragm and the nozzle. These refine and smooth the treble by masking resonances from unwanted energy and removing unwanted peaks in the upper frequencies. In addition, a complex shape called an acoustic vortex, is milled into the nozzle for the most natural sound wave propagation.

The X3R transducer is a refined version of Sennheiser’s 7mm Extra Wide Band transducer. During assembly, precision cameras examine all the components during production, and the transducers are tested before and after pairing, the left and right earphones are paired by hand to make sure they work well together. In addition, a newly developed foil membrane continues the inner dampening, and a milled acoustic back-volume chamber shapes the bass and mid-range frequencies.

The packaging was sturdy and complete with every thoughtful item one could need.

Tips are critical in getting a proper seal with any IEM, and Sennheiser has provided small, medium, and large tips in both silicone and Visco memory foam. These are custom-designed and have a filter within the tip.

Included is a very sturdy zippered carrying case, with the serial number and “Made in Ireland” stamped on the back, as well as a signed and dated inspection sheet.

A thoughtful touch is the addition of both a cleaning cloth and a cleaning tool.

Three 1.25m oxygen-free, para-aramid reinforced cables are included with a 4-pin 2.5mm balanced, a 3-pin 3.5mm unbalanced, and a 5-pin 4.4mm balanced jacks. Bendable ear hooks make getting a secure fit easy.

Setup

As with any IEM, the first step is finding the right ear tips. Looking at the wide array, I was sure I would find an easy fit. I was wrong. Memories of CanJam and my failure to listen to IEMs because I couldn’t find any that fit my ear returned. I was puzzled. One of the reasons I was able to audition the IE 900s was because they did fit. I went through every size and both materials. I was frustrated and embarrassed, as I had specifically asked to review these. Of course, playing music without a proper seal is awful; no bass, and is thin sounding. I started looking online for aftermarket tips. However, as I studied the Sennheiser tips I noticed there is a foam insert just inside. Clearly, this is important, as it protects the nozzle from ear wax. I decided to stay with the Sennheiser tips. I studied the manual and the drawings on proper insertion, including the advice to compress the foam tips for 15 seconds before inserting. I did this and gave a twist I hadn’t tried before and voila! The insertion does take practice; the shape requires some twisting while holding the ear hook. It finally became second nature, and I was on my way. I think an instruction video on Sennheiser’s website showing how to fit the earphones into the ears would be very helpful and reassuring.

I have two set-ups I use. At my desk, I use the Pass Labs HPA-1 Class A headphone amplifier, which I power through a Claris Sextet Power Conditioner, with the 2.5mm cable, and with my iPhone, I use the portable Earmen Colibri DAC/amp and I switch to the balanced 4.4mm cable. Either source provides rich and detailed sound, and I’m happy using either system. Qobuz is my primary music source.

In Use

Sean Johnson and the Wild Lotus Band, “Devaloka”, 16-bit CD quality 44.1 kHz- Stereo via Qobuz

I stumbled across the music of Sean Johnson and the Wild Lotus Band when Siri had picked it out as music I would like…it was playing in another room. I stopped and listened. The chanting drew me into my office where it was playing. I sat down and almost fell into a trance. I was pulled back to memories of the call and response of chanting I experienced in meditation groups. For me, there is something instantly heart-opening when people chant/sing together. The melodies and words were familiar in the chanting, yet there was also a jazz/blues influence, including electric guitars that sparked my curiosity. I found the Wild Lotus Band on YouTube, and I was smitten. Based in New Orleans the phrase, “the confluence of the Ganges River and the Mississippi Delta” caught my eye. Traditional Indian devotional chanting blended with the cultural influences that make up New Orleans blues/jazz create a mesmerizing sound that is melodic yet fiery and complex. The musicianship is stellar. There are the influences of American gospel, blues, jazz, sacred chants from around the world, and even a touch of Celtic.

Asato Ma (Illumination) opens with a deep gravelly almost bass guitar. One of the strengths of the Sennheiser IE 900 is how powerfully it reaches into bass and sub-bass notes, preserving the detail and shadings that open this song. Male and female voices join in, and, again, the IE 900 presents all the textures and resonances of both the male and female voices warmly and with precise placement. Each Sanskrit word is clear and crisp. The Harmonium drones under the building layers as more instruments and voices join in. The soundstage the earphones produce is superb. I don’t think of IEMs as producing a wide soundstage, yet there is both width and depth here that is more headphone-like than IEM. This is a lovely recording and shines with the IE 900.

Tomoe-ryu Yutakadaiko, Joji Hirota & the London Taiko Drummers, “Discover Japanese Taiko with ARC Music”, Harvest, 16-Bit CD Quality 44.1 kHz- Stereo via Qobuz

Taiko drumming has its roots, like many world cultures, in the use of drums in battle to unnerve enemies. The history goes back at least 1400 years, and the use of drums grew to be included in Buddhist and Shinto rituals and incorporated into the Imperial court music. The Taiko drumming we are familiar with is a recent arrival, having been developed in 1951 through the work of Daihachi Oguchi, a master drummer who was a former jazz drummer. Taiko was introduced to the world at the 1964 Tokyo Olympics. Daihachi Oguchi explained the power of Taiko this way “Your heart is a taiko. All people listen to a taiko rhythm dontsuku-dontsuku in their mother’s womb. It’s instinct to be drawn to taiko drumming. In taiko, man becomes the sound. In taiko, you can hear the sound through your skin”.

Taiko drumming should be experienced live. You really do feel the drums “through your skin”. I’m not sure what possessed me to think I could enjoy Taiko drumming through any kind of headphones, much less an IEM, but I thought it might be a good test. Well, it was more than a good test; it was powerful. The piece, Harvest, starts with lively solo drumming but is quickly joined by a cacophony of bells and cymbals. Soon more drums of different sizes and tones join in, and the drumming takes on a jazz-like quality. There is almost a Gene Krupa-esq rhythm and tone to the piece. It was startling how deeply and forcefully the slam of the drums was presented through the IE 900. I kept visualizing the cross-section diagram of the parts, and they were all tiny. How do they make this big, rich sound?

Kraftwerk, “Autobahn”, 16-Bit CD quality 44.1 kHz- Stereo via Qobuz

Going from Japan to Germany, I listened to Kraftwerk’s hypno-pop “Autobahn”. Although Kraftwertk’s first three albums were groundbreaking, it was the hypnotic song Autobahn on the album of the same name that brought the group’s electronic music to the mainstream. The 22-minute title track, in a severely edited form, became an international hit single in 1974 and remains the peak of the band’s achievements. The first time I heard Autobahn (and it should be heard through headphones to get the full effect of the intro sound of an old jalopy engine starting and the car noisily moving from left to right, gears grinding and whining the whole way), I was hooked. The farewell toot makes me laugh every time I hear it.

This masterpiece of electronic music is perfect for headphones as Kraftwerk makes full use of stereo imaging as it creates the sound of cars whizzing by. I love the pure tones of electronic music. Bass has a clean depth that may not have the resonances of natural instruments but is pure and punchy. The variety of tones has its own rich beauty. They are used playfully and with humor and in Autobahn I dare anyone to be able to sit without bopping around.

This German song sounds like something the Sennheiser engineers would love, or so I imagine. If you were driving 125 mph on one of the stretches of the Autobahn that has no speed limit, and you were listening to the original 1974 version, you would travel 45.83 miles. Just say’n.

These IE 900 shone brilliantly. There is a lot going on in this piece of music and they had no trouble keeping everything separated while keeping the stereo imaging wide.

Steve Tyrell, “Back To Bacharach”, This Guy’s In Love With You, featuring Herb Alpert and Burt Bacharach, Hi-Res 24-Bit, 44.1 kHz- Stereo via Qobuz

There are a few songwriters whose contributions over the decades become the American soundtrack. Paul Simon is such a writer and so is Burt Bacharach, whose music is so widely recorded that the songs can almost be a cliché. But when performed by someone as accomplished as Steve Tyrell, singer, producer, and composer, who has a deep love of American Standards, it takes on a fresh sound, as if performed for the first time. When he was head of A & R and promotion at Scepter Records, he championed Dionne Warwick’s recordings of Burt Bacharach/Hal Davidson compositions. In 2003 he recorded “This Guy’s in Love”, honoring the music of Burt Bacharach.

Burt Bacharach’s lively piano solo introduces the song. The IE 900 captures the timbre of the piano beautifully. Steve Tyrell’s rich crooner’s voice is placed in the center with warmth and fidelity to his slightly gravelly voice. The strings join with the piano, and the sound of Herb Alpert’s trumpet joins the chorus and then leads them out to the finish.

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Conclusions

These are not inexpensive, but in the pricey high-end world of some of Sennheiser’s competitors, they are something of a bargain. The packaging is complete with attention to every detail of what the listener might need. The cleaning tool and cloth are a thoughtful touch, and the cables and connectors are high quality. The silicone and memory foam tips are well thought out, though some users will have to shop outside the Sennheiser ecosystem to find tips that fit. This is a complete package giving the listener all the tools needed for years of listening.

Likes

Tiny and comfortable.
Easy to wear for hours of listening and great for travel.
The sound is rich and rewarding.
The cable collection is complete with different sizes for various music sources.
Beautiful, subtle and understated. No Bling.
Superb construction. These are intended to last for years of ownership.
Generous warranty.
Responsive customer service.

Would Like To See

An information video on how to pick out the correct tip, and how to insert them. I’m probably not alone in the frustration of figuring out how to give an IEM a proper fit. I wouldn’t be surprised if some people just give up and think an IEM just isn’t for them when it is just a matter of a bit of education on proper fitting.

The Sennheiser IE 900 represents the highest level of engineering in a tiny, aluminum housing. The sound that is possible when the earphones are properly seated is extraordinary. As I mentioned, I’m primarily an over-ear headphone lover, but the month I spent with these has shown me there doesn’t have to be a sacrifice of the sound in exchange for the convenience of an IEM. The tonal presentation is natural, neutral to slightly warm, and detailed. The soundstage is wide for an IEM and even exceeds some headphones I’ve listened to. I think these would be great for travel, and they do a good job of noise isolation when properly sealed. The bass response is astonishing and well-controlled. Complex music never gets smashed together but is presented with clarity and precise placement. The treble is nicely controlled; there is sparkle but no harsh peaks. Voices are handled nicely though the mids are somewhat recessed compared to the bass and treble, but I think that is just because those are so outstanding.

If I was handing out stars, I would give these 5 stars.

Lory Hawley

I was born to love audio. My grandfather was awarded a patent for a “METHOD OF PRODUCING TALKING-MACHINE RECORDS” in 1912. He also sang opera. He passed his passion for music and the early days of recording on to my mother, who then passed it on to my sisters and me. My father, a professor of electrical engineering, was also an amateur jazz guitarist. He loved Heathkit’s home-built electronics, and as a little girl I was his “assistant builder”. He always talked to me about what he was building, and we always had the biggest T.V. and the most advanced HiFi gear. Music was always on in our house, and my folks really listened to and discussed what was playing on the turntable, and later the reel-to-reel deck. I grew up with jazz, the classics, and my father’s goofy and extensive collection of comedy albums and sound effects records. He always made sure I had the latest transistor radios, which were my prized possessions; I could be found late at night, trying to listen in on the faraway stations that magically appeared through the static between my local stations. In the early 70s, I discovered the remarkable world of Japanese audio on my layovers in Japan as a flight attendant. I remember lugging home a huge, very heavy wood-clad Kenwood receiver back from Japan, thanks to a kind captain that made space for my treasure in the cockpit. That receiver powered my two Bose 901s that I had hung from the ceiling in the living room. I also fell in love with the early Sennheiser open-back headphones that had come on the scene in 1968 and which sparked my passion for headphones that continues to this day. After traveling the world as a flight attendant my work led me to the restaurant world of the San Francisco Bay Area, where I spent several years working in a “farm to table” restaurant. I developed a passion for photography while co- writing a cookbook with the chef. My skills as a food and garden photographer grew and I added working as a photojournalist with assignments that usually included the food scene in the Bay Area. A year ago, I joined the San Francisco Audiophile Foundation (https://audiophilefoundation.org), where I discovered my tribe. It was humbling to find out that compared to almost everyone I met, I actually have a long way to go to call myself an audiophile! I was also shocked to find out that out of over 300 members, there were only three women (including me). It was a source of pride, however, to know that the president and a founding member is a woman. Yay, team! You can find me outdoors hiking and photographing landscapes and wildlife and trying my hand at nighttime landscape photography.