Hardware Reviews

Sennheiser IE600


Even before my days working behind mixing desks in BBC studios, I was a fan of headphones. They provide a unique and personal listening experience as well as the ability to shut oneself away from the surroundings and enjoy music without interrupting others. 

Over the years I’ve used a variety of headsets from a variety of manufacturers although many have been from the Sennheiser stable: starting with the 414s I used in Broadcasting House in the 1980s to the HD25s I donned as an on-the-road reporter in the 1990s, to my faithful CX300II in-ear variety which have been a trusty companion on travels around the globe for nearly a decade now.


The latest arrival from the revered German brand attracted my attention because I am in the market for replacement headphones for personal listening on the move. I have tried the Bluetooth-connected wireless model intended to partner my iPhone but didn’t really get on with them. They were not comfortable, I felt the sound quality was compromised over that which I know is possible from in-ear transducers, and I was terrified that they would fall out at any moment and either become lost or damaged beyond repair. I am much happier with the traditional approach of a cable connection.

So it was that a beautifully packaged pair of Sennheiser IE600 in-ear wired headphones arrived for this review. The box alone shouts that this is a quality product and one aimed at the discerning listener, that is further qualified by the £600 price tag although, as we shall see, it’s certainly not excessive for the offering.

As someone who puts fidelity before convenience, this product is probably aimed squarely at me, and I wasn’t to be disappointed because these small in-ear devices produce an impressively large and immensely detailed sound with superb levels of neutrality and a well-balanced soundstage. 


Central to the IE600 is a single full-range driver rather than the technology adopted by much of the competition of dynamic driver and balanced armature. The approach allows for better matching between left and right and Sennheiser claims to have achieved the best in the market. Thus, we have 7mm capsules (since headphones are really microphones in reverse) promising extra-wide range and labelled TrueResponse.  

The sturdy box contains two cables with gold-plated MMCX plugs: one terminated with an unbalanced 3.5mm (as expected) and another with a 4.4mm balanced connector where this is required. There is also a 2.5mm option, available as an accessory. I used a simple Apple to 3.5mm adaptor to connect the IE600 to my iPhone and plugged them directly into a Macbook for auditioning purposes.

I was expecting the unit to have been put together in the German facility, near Hanover, that I had once visited to witness incredibly advanced radio microphones being assembled alongside an impressive R&D department. But, no, these IE600s are hand assembled in Ireland. The earpiece metal shells are made over in Germany though, and from aviation-grade and highly durable ZR01 amorphous zirconium. This makes them strong: the material being three-times as hard and three-times more resilient to bending than steel. Then the special coating is applied, making it resistant to scratching or corrosion and aiding longevity. Attention to detail continues inside where we have an acoustic rear chamber as well as a pair of dual-resonator chambers at the nozzle end, all to aid the masking of unwanted resonances. 


The cable becomes an adjustable ear-hook to loop over the ear, and can be moulded to shape for best fit and comfort. Even wearing spectacles I had no difficulties in achieving a nice fit. In the box are a selection of compatible ear tips: small, medium and large, in both silicone and visco-foam with memory effect. These allow the earphones to sit comfortably and securely in the ears. Fitting the foam ones is slightly more involved but is worth the effort. The downside is that, due to their natural properties, they have a short lifespan of just a few months before they need changing. A cleaning tool is provided to remove any earwax which becomes lodged in the caps during use, or remove and simply clean with warm water as required. 

Sound quality
Since much of the design comes from the flagship IE900 model (priced at £1,300) it is perhaps unsurprising that the sound quality of the IE600 was generally superb. I listen to a lot of speech-based material while on the move, in the form of audiobooks, podcasts and BBC Radio 4, and my immediate sensation was how voices are not only most naturally portrayed but so lifelike. It is as though the source is right there, beside the listener having a private conversation. 

With musical sources, too, the designers have been clever in creating a bridge between the listener and the music in such a way as to bring the two intimately close. On choral works the human voice was to the fore in a most enjoyable and involving way. With the 2002 recording of Bach’s Magnificat (Collegium Vocale Gent under Phillippe Herreweghe on Harmonia Mundi) there may only be a dozen minutes of choral singing but they are among the most demanding minutes of his output. The IE600 brought them to me in a most exciting way, with festive bursts of colour and exuberance, before delivering the delights of solos that retain all the pace and dynamics captured on the disc.


I was surprised and delighted at just how detailed the sound was; these are monitor-quality headphones in that they are really analytical of the input source. That’s not to say they are in any way tedious in this regard, rather that they are able to dig deep into the music and extract micro components of detail to excite the listener by revealing more of the performance. This became clear with Rossini’s Barber of Seville (Decca/1989) as I could feel every breath of seasoned performers Cecilia Bartoli and Enrico Fissore. The captivating clarity and bell-like resonance of the singing was spine tingling. 

During a somewhat tedious bus journey dogged by the roadworks of East Sussex, I upped the tempo and played Phil Collins’ But Seriously from 1989 to relieve the stop-start frustration. This revealed the IE600s ability to dig deep in both detail and LF retrieval to expose a bottom-end of quality and extension. The bass is not only controlled and substantial but in perfect proportion as to bring the entire performance to the listener with true realism, taking me from that 29 bus to the recording studio. Speed and agility were shown to be added traits of these headphones as my feet began to tap involuntarily, perhaps to the surprise of the only other passenger aboard. 

Back to human voice as it was time for the World at One current affairs programme, and I was reminded of just how good the midrange performance of these tiny transducers was. So natural, effortless and everything in the right proportion. No hint of sibilance, or nasality or chestiness as one so often finds from inferior ‘phones. The only small criticism I could make is regarding the HF extension which at times sounded a mite over-done, but that’s not to say it wasn’t on the recording or live broadcast. Testing this out with known tracks, including Runaway Horses live from Berlinda Carlisle, the usual exuberance is slightly exaggerated but not in any unattractive way. And, better this than any muting of the treble response so as to lose sparkle and liveliness. 


I did encounter one issue I’ve seen reported by other headphone users although not something I can say I’ve experienced before: cable noise. As the flex rubbed against my clothing it generated the odd rustle which could be easily eliminated by re-routing the lead over, rather than under garments. But it’s a point to bear in mind. However, even after a short auditioning period I am more convinced than ever that ‘wired’ beats wireless by a mile as far as sound quality goes. It also doesn’t cause the battery drain encountered with Bluetooth connectivity. Thus, the IE600s win my personal seal of approval. 

Having used the Sennheiser IE600s they are now a must-have on my travels, and take pride of place as a permanent fixture in the tote bag that goes everywhere with me. Yes, they are not a budget-price. But then they are far from budget-level headphones. Here we have a well-engineered and superbly built design which is comfortable to wear, even for extended periods. The cost is easily justified by the build and sound quality. Highly recommended and now an essential part of my daily travel kit.


Type: wired in-ear monitors
Ear coupling: intra-aural 
Transducer principle: dynamic 
Driver size: 7mm
Sensitivity: not specified
Frequency response: 4Hz-46.5kHz
Maximum SPL: 118 dB at 1kHz
THD: < 0.1% @ 100 dB
Impedance: 18 Ohms
Cables: 125cm para-aramid reinforced cables 
Connector: MMCX to 3.5mm and balanced 4.4mm
Weight (w/o cable): 6g each
Warranty: 2 years

Price when tested:
£599 at time of publication
Manufacturer Details:

Sonova Consumer Hearing GmbH


in-ear headphones


Trevor Butler

Distributor Details:

Sennheiser UK Ltd

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