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Sennheiser IE 900

In terms of ‘proper’ headphones and earphones, there are precious few that could elbow their way past Sennheiser in the recognition and appreciation stakes. This is hardly surprising as the brand has been at it for well over 50 years. It’s first high quality, open-back headphone was launched way back in 1968, around the same time as The Beatles’ White Album

More recently, the brand’s consumer division (headphones, earphones, soundbars) was sold to the Swiss company, Sonova Holding AG - a leading provider of hearing care solutions. From which there is already evidence of a technology coming together with the recently released wireless, ‘Conversation Clear Plus’, of an in-ear device that sits halfway between a hearing aid and an earphone, to help provide effortlessly clear conversations in noisy environments’. This feels very much like work in progress, and it will be interesting to keep an eye out for future developments.

However, there is certainly nothing antiquated about the wired, IE 900 earphones. These sit confidently and comfortably at the sharp end of the audiophile market, promising (and delivering) uncompromising and captivating quality. The £1299 IE 900 tops the range of the three, wired in-ear models. The others are the IE 200 (£130) and the IE 600 (£700).

As you may expect, expensive, wired earphones - no matter how classy - are never going to sell in massive numbers, although it is reassuring to find that the Certificate of Authentication in the presentation box explains that the IE 900s are engineered in Germany; hand-assembled in Ireland; and undergo thorough inspection and testing before leaving the factory and arriving with the customer. They can be bought from a few retailers, or from the Sennheiser website.

The earpieces, while miniscule, are distinctive. With a sharp design, full of character and modernity. The housings are beautifully milled from a single block of aluminium with attractive, closely spaced contour lines. The familiar, stylised ‘S’ logo is slightly raised on the outer side of each earphone with the IE 900 ident etched on the inside of left housing in rather unnecessarily large lettering. The right earpiece has a small red collar between the housing and MMCX cable termination so you can easily identify which earpiece goes in which ear. The cable too has a L and R indication but so subtle, it is easier to miss than to see. Each earphone weighs just four grams, meaning that there is absolutely no chance of any complaints of feeling a weight on your head, such as with a pair of over-ear headphones. And while the look and design exude quality, this is nothing compared to what you can’t see, hiding within their tiny form.

Inside is Sennheiser’s unique ‘X3R technology’ that produces their highly revealing sound. Instead of using a system of multi-drivers, Sennheiser has worked on its ‘one-driver principle’ by further developing its ‘7mm TrueResponse’ transducer: a single, miniscule, high-performance dynamic driver that ‘avoids the sonic obstacles’ that can be introduced by multi-driver arrays. The aim of this system is to deliver a wide frequency range with low distortion. In other words, a system that allows us to hear more detail and to get a truer, more realistic sound performance. 

A further refinement of its unique technology are the three resonator chambers, precision-drilled into the aluminium chassis between the transducer and the nozzle through which the sound is funnelled into your ear. The aim of these is to smooth the response at high frequencies so that you can hear more detail. The expertise of dealing with such minute surface areas and components and the resulting full fat, insightful sound, is a demonstration of truly exemplary engineering.

Sound quality

It’s hardly a revelation but IE 900 responds best to equipment of a similar quality - the better the source, the better the result.  Listening to hi-res recordings loud and brash or quiet and considered, the results possess oodles of subtle detail with rich, enticing performances.

Sennheiser asserts the point that these technologies are designed to deliver compelling results at low volumes and, as someone that isn’t a fan of having the top of my head blown off, it certainly is appreciated. While listening at what are ‘normal’ levels for me, the results are exquisite in detail. For example, on the extraordinary recording, Poem of Chinese Drum (Hok-Man Yim, Tidal, CD quality) an excellent example of attack and decay, the IE 900s perform magnificently. You feel as though you are inside the drum! In fact, all of the tracks played had a clarity of notes, a real precision, but not at the expense of musicality and engagement. Feed the IE 900’s a diet of good, hi-res quality and they will provide you with a delightful banquet.

Living with 

Within the IE 900’s elegant packaging, there is a decent selection of useful bits and pieces, including 3 different sized earbuds in both memory foam and silicon. I found the foam more comfortable; the silicon was a bit too unyielding after longer spells. It’s worth taking a bit of time to ensure that the buds are well seated in your ear canal to get the best sound experience. If you do, even on quiet tracks, extraneous sounds are massively diminished. The IE 900s are extremely effective at keeping the annoying outside world at bay. For me, comfort is an important consideration, and the lightweight IE 900s score highly with an almost negligible presence in terms of pressure on the interior of your ear.

There are also three cables supplied: 2.5 and 4.4mm jack plugs for balanced sockets and 3.5mm for the more conventional. Each with a stiff sleeve around the ear bud end that allows you to bend the cable around your ear for a custom fit.

I found the cable quite susceptible to transmitting noise if it is banged or brushed up against something with any kind of force. It becomes particularly evident on very delicate tracks such at the test track from Kayhan Kalhor and Toumani Diabaté. This experience can be described as only slightly annoying rather than truly irritating as it is easier to just learn to be calm and minimise fidgeting so that the issue does not arise. I wanted to change the cable in order to see if this would make any difference. However, this wasn’t possible as, although the connections are standard MMCX, they are recessed into the earphone housing ‘to alleviate bending stress’, meaning the connections of independent cables don’t match. The result is that you are confined to the Sennheiser cable, a minor inconvenience at best.


Although there is no doubt that the IE 900 is suited to any style of music, some may feel that the bass doesn’t do quite enough to rattle your fillings. That’s just because they are accurate, without needing to distort the facts, so to speak. With old hi-fi show favourites, such as Massive Attack’s Angel, the bass is there in spades but the IE 900s don’t make assumptions by adding something that isn’t already on the recording. What they will not do is turn poor into great, if the recording is under par, it’s going to sound the same, these are not some sort of magic wand for spinning straw into gold. In other words, if you want to listen on your phone, without a portable dac, for example, these are an extravagance that you can probably do without. If you’re looking for a partner to your hi-res portable player or a tasty home-based amp, and the rewards flood through.

Listening notes

Berliner Philharmoniker Shostakovich Symphony No. 9  

This bounces along, full of life. The Philharmoniker, under the baton of Kirill Petrenko, sounds as if it is having a great time. Criticised in a review from 1946 – “The Russian composer should not have expressed his feelings about the defeat of Nazism in such a childish manner" – this is uplifting, joyful piece, is brought to life by the IE 900s.

The expression and clarity of this recording (Hi-res, Qobuz) bursts with energy. You even experience the intakes of breath of the woodwind players and there’s a wonderfully controlled depth from tympani and strings, without ever pushing their way to the front.

First Aid Kit Turning onto you

A Swedish sister duo, who sound as if they come from Arkansas, deliver highly accomplished Americana. The Sonderberg sisters’ wonderfully haunting voices sound crystal clear while the backing knows its place and never muscles in for a takeover. They wanted to create an ‘old school country soul vibe’ – and it’s achieved with ease. It is never harsh or grating with the IE 900s carefully capturing all the nuance and subtlety, that could have easily tipped in cheesery, but thankfully, not a chance.

Kayhan Kalhor and Toumani Diabaté The Sky Is The Same Colour Everywhere

Kayhan Kalhor is an Iranian-Kurdish player of the stringed kamancheh and the lute like setar, Toumani Diabaté is a Malian kora player. Together they make magic. It is delicate and refined, where the shaping of notes and sounds, however strange, are the essence of the performance. The occasional slap on the gourd end of the kora provides a wonderfully long reverb, which is a delightful and relaxing experience

What the press say

Why you should buy it

Elegant, extremely competent, comfortable and a delightful personal route to hearing music of the highest quality, depending on the source. All without inflicting the fatiguing weight of headphones on your bonce

Video review

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