My parents used to own a $500 car. That car drove me to school as a kid, picked up groceries, and it definitely stalled at intersections. Once you start seeing earphones for $1,300, consider that as used car territory. Even with inflation, I ask: is nearly $1,300 wise to spend on in-ear monitors (IEMs)? No, it’s not wise, but it’s kind of fun. The German-manufactured Sennheiser IE 900 works well and effortlessly (unlike that aforementioned Ford), but the market is full of heavy hitters. Let’s see if the premium IE 900 justifies the cost.

Who should get the Sennheiser IE 900?

  • Audiophiles interested in the prestige element of gear will like the upgraded IE 900 experience.
  • People with money to burn on portable audio will be rewarded with very nice in-ear headphones.

What’s it like to use Sennheiser IE 900?

The Sennheiser IE 900 coiled up in a hand.

Wired listening offers a consistent, high-resolution listening experience.

Part of the IE 900 experience includes taking the time to enjoy the tactility of the earphones. The lightweight aluminum milled housing slips into the ear like a ring on your finger. After all, this is a marriage of sorts between you and Sennheiser, in the way that Sennheiser supplies signed paperwork and you share your finances. Getting the right fit is important because the majority of the IE 900 features hinge upon it. If the supplied ear tips do not fit you, I urge you to try a third party option. A poor fit negatively impacts isolation, and by extension audio quality.

Related: Best Sennheiser headphones

In my ears with the size small foam ear tips, the IE 900 is comfortable, but it sits pretty deep in my ear canal, which creates a feeling of pressure. The silicone ear tips are less obtrusive and I can leave them in for longer without much fatigue, though they don’t isolate as well. Despite having a similar look to the Sennheiser IE 300, the IE 900 feels more comfortable for longer periods. With this style of earphone, I notice that when I bob my head to a song’s bassline, the sound noticeably alters because movement shakes the IE 900 out of place. Even though the fit is secure, it’s very sensitive to tiny changes.

What does the extended frequency response actually get you?

A man from the side wears the Sennheiser IE 900 earphones outside in front of greenery.

Like other models in the IE lineup, the IE 900 is designed to go over your ears and down behind you. This works but can get in the way sometimes.

The IE 900 frequency response ranges from 5Hz to 48kHz. While that number looks impressive, the vast majority of people can’t hear above or below the 20Hz to 20kHz range. Some of us like the extended response because we think we can perceive it. Indeed, some people can “feel” those sub 20Hz low frequency and infrasound bass frequencies even if their ears and brain can’t interpret them. Meanwhile, only a few unusual (and likely, young) people can hear sounds above 20kHz—think dog whistle frequencies. Try testing your hearing.

Learn more: High bitrate audio is overkill: CD quality is still great

Even if you could perceive those high and low frequencies, there wouldn’t be much to hear, because that’s not where our music lives and not what standard recording equipment registers. The 5Hz to 48kHz range isn’t necessary, just like buying a Bugatti hypercar capable of reaching illegally high speeds—though, at least you know you could experience extreme speeds if you were allowed to. You can’t even experience 48kHz.

Does the Sennheiser IE 900 work with Bluetooth?

CLose up of the buttons on the Sennheiser IE 100 PRO Wireless BT Connector, shows a multi function button, volume, and pairing button. There's also the battery pack and a single earbud visible.

On the right is the Sennheiser IE BT Connector (which would need to be purchased separately) with its small battery pack, and a control and mic module. The cable plugs into the buds like any other MMCX connection.

The IE 900 can work with the Bluetooth Sennheiser IE BT Connector for portable playback, which we reviewed with the IE 100 PRO Wireless. While you can use the IE 900 to stream wireless audio, it sort of defeats the purpose of the product. For most folks, casual listening doesn’t require high-resolution audio, and the individual who purchases an audiophile product like the IE 900 looks for the features like the extended 5Hz to 48kHz frequency response, which Bluetooth can’t support.

What do you get with the Sennheiser IE 900?

The Sennheiser IE 900 open case with included detachable cables, different sized ear tips, and cleaning tool, all set on a wood surface.

Sennheiser includes six ear tips, and three different detachable cables depending on your audio source needs.

Prestige is the first word that comes to mind, as I open the box for the IE 900. Sennheiser places a certificate of authenticity within each box that promises this set has undergone a quality check, and each pair of transducers has been hand-selected. You get a signature (in ink) and the handwritten serial number of your in-ear monitors on the certificate, as well as on the somewhat hefty carrying case. The case works well, but it’s too clunky to fit anywhere but your desk, backpack, or large purse.

Six sets of ear tips (three made of foam and three made of silicone) come in the box along with a cleaning tool with a microfiber cloth, an optional lapel clip, and three choices of hardy para-aramid cables round out the bundle. Generally, I use the standard 3.5mm connection for my lossless audio listening. Sennheiser also ships it with 2.5mm and 4.4mm cables. The MMCX cables satisfyingly snap into place. Subtle L and R indicators on the housings direct you which goes where. The cable has a gentle memory wire that holds it in place when bent and curved over the top of the ear.

Does the Sennheiser IE 900 have good isolation?

Image shows chart of Sennheiser IE 900 isolation attenuating between 10dB and about 45dB of noise.

You find no fancy active noise cancellation here, but instead impressive isolation from good engineering and a well-sealed ear.

Yes, isolation is great with the Sennheiser IE 900. You don’t get any new fangled active noise cancellation (ANC), but that just means there’s one less point of failure to worry about. Isolation costs you zero power (it’s nice to not charge headphones, right?), and great isolation results from solid engineering. You can effectively block out anyone on the bus trying to talk to you. You won’t even know if bus neighbors are chatting up a storm because the IE 900 successfully isolates you via the effective physical barrier that comes with a well-sealed ear.

Typically isolation does its best work with high-pitched sounds, and the Sennheiser IE 900 is no different. It does, however, sweep the spectrum with at least around a 10dB reduction of sounds across the board and up to around 45dB in the high mids and treble.

How does the Sennheiser IE 900 sound?

The image shows the Sennheiser IE 900 frequency response as measured against our ideal studio frequency response.

Landing somewhere in the pleasant world of not quite consumer and not quite studio (our house curve seen in pink), the IE 900 (in blue) straddles the line between neutral and consumer for close, but fun listening.

The $1299.95 question is, how does the IE 900 sound? It sounds good. It sounds like if you combined a consumer frequency response with a studio frequency response. The bass and midrange response hews closely to our consumer target curve. Meanwhile, the upper-mids and treble resemble our ideal studio frequency response, with some light under-emphasis. This yields a highly pleasant listening experience, nearly devoid of any notes drowning out others. If anything, you will hear quirks and interesting mixing decisions laid bare with this frequency response.

Lows, mids, and highs

Bass frequencies from the kick drum and bass guitar sound just loud enough to hear in the song The Ghost with a Hammer in His Hand by Help Stamp Out Loneliness, and don’t mask other frequencies. For the bass frequencies, ensure the buds fit all the way in your ear because if they shift the bass disappears. Just when you think the IE 900 earphones are in, push each in further. Honestly, it feels just short of surgical.

A hand holds the Sennheiser IE 900 earphones without the cable attached.

A detachable cable means you can use the IE 900 for years without having the buy a whole other new set if the cable fails.

Listening to a track like The Ghost with a Hammer in His Hand could easily cause listener fatigue if played through a cheap set of earbuds, with trebly organs and synths in the mix. Instead, the IE 900 pleasantly relays keyboard sounds thanks to the slight treble under-emphasis relative to our studio headphone curve. One side effect of the under-emphasis is that some female voices sound inaccurate, as if they lack detail. D. Lucille Campbell’s low alto voice lacks an equivalent emphasis on some of the higher-register frequencies.

Related: Best studio headphones

Picking a more guitar-focused song, Sunlight Bathed the Golden Glow (Remastered) by Felt once again reveals that the IE 900 is fully capable of reproducing treble notes with just the appropriate amount of emphasis. Maurice Deebank’s meandering lead guitar is reproduced faithfully. Since there’s very little auditory masking here—especially relative to consumer-oriented headsets—the IE 900 reveals interesting artifacts of production. It’s more obvious the producer used a filter to remove the singer Lawrence’s sibilance (at 2:04 for example). If you are an analytical listener the IE 900 can highlight your favorite band’s flubs or quirks.

Sennheiser IE 300 vs Sennheiser IE 900

The image shows the Sennheiser IE 300 frequency response as compared to the Sennheiser IE 900, as compared to the SoundGuys studio frequency response ideal. They are fairly similar.

The dotted-yellow is the Sennheiser IE 300, blue is IE 900, and the studio ideal is in pink. You’ll notice some similarities in the mids and bass.

You may ask yourself if the Sennheiser IE 900 is worth the extra $1,000 USD over the Sennheiser IE 300. That’s a sane question, and for most people, the answer is no. Then again, “most people” is not the target demographic for the IE 900. Most people are happy with the already low distortion of the IE 300, and the solid-sounding frequency response. Additionally, most people are happy if the transducer is made in Germany on the IE 300 and the rest of the labor is performed in China.

The Sennheiser IE 300 shot with a shallow depth of field, rest on a synthesizer.

You don’t get sleek aluminum housing on the IE 300, though the shape is somewhat similar to the IE 900.

The IE 900 is for that other tiny percentage of people who want an even lower distortion, even if the difference is scarcely perceptible. These consumers value knowing that the whole of the IE 900 is made in Germany with double-tested, hand-matched transducers. This has to do with both the element of prestige as an owner, but also an invitation for you to try out Sennheiser doing some of its best work. The IE 900 is the earphone equivalent to a car manufacturer deciding to build and sell a concept car, rather than selling the more reasonable, sane version—the IE 300 in this case.

Anecdotally, the IE 900 fits my ears better, despite looking very similar in shape. Most of us ought to pick the IE 300. Those who choose the IE 900 (hopefully) understand the law of diminishing returns and are willing to pay extra to get those minute differences.

Should you buy Sennheiser IE 900?

The Sennheiser IE 900 dangles over a Newton's Cradle on a wood desk with a plant in the background.

The aluminum housing feels premium and has the added advantage of a lightweight, robust build.

For the individual who has everything else, the IE 900 sounds great. For the rest of us, it’s a prestige product that has cheaper alternatives that get you 90% of the way there.

There is something strange about listening to music on earphones that cost more than the ones the musicians used when producing said music. The Sennheiser IE 900 experience is complex because if you casually listen, it sounds about as good as very good earphones. If you actively pay attention to what you hear, suddenly the clarity of all instruments in different frequencies becomes noticeable.

With that said, you can’t talk about the Sennheiser IE 900 without acknowledging the price tag. Ordinarily, as consumers we all look at a product and say, well I wish it had X, but at this price, I understand why it’s not there. You don’t have to do that with the IE 900. The price begs you to be critical. The IE 900 should be even more comfortable, and wrapping a cable over your ears feels annoying. For basically $1,300 USD, you should get something approaching custom-molded earbuds.

Related: Best headphones under $1,000

In a world of compromises and rational decisions, there’s something to be said for supporting manufacturers trying to make the best audio gear. For that reason Sennheiser deserves credit.

Sennheiser IE 900
All prices listed in USD unless otherwise specified. Prices may change over time, and vary by region. Unfortunately, we cannot list Amazon prices on the site, as they vary greatly by currency.

What should you get instead of the IE 900?

The wired cable plugged into the Sennheiser IE 100 PRO with ear tips and cloth bag, sitting on a wood surface.

With the lightweight and low profile buds, and the over-ear cabling, the IE 100 Pro stays put.

The clear answer is to buy the Sennheiser IE 300 instead. If you have a tight budget, try the also excellent Sennheiser IE 100 PRO Wireless. Both sets of earphones have similar frequency responses to the IE 900. The IE 300 has a bit less treble emphasis than the IE 900, but it performs very well. Meanwhile, the IE 100 PRO Wireless has a touch more treble emphasis. It feels less comfortable over an extended period of time than the IE 300 and IE 900, but keep in mind it runs for about $150.

What’s great about choosing one of the other products in the IE series is that cost-cutting measures haven’t ruined sound quality or frequency response. You don’t get the full suite of memory foam ear tips with the IE 100 PRO Wireless, but you can buy those for under $20. There’s a Sennheiser IE for everyone.

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