Sennheiser IE600 review: elite in-ear wired headphones for the discerning listener

In this Sennheiser IE600 review, we're looking at a pair of  in-ear monitors that take the old-school nature of wired headphones and add a couple of spins of their own, bucking the trends for driver design and external materials.

The Sennheiser IE600 are arriving in a world where portable listening is all about wirelessness these days – but the best wired headphones will always win out with those who prize the fidelity of sound reproduction over anything else.

At their high price, the Sennheiser IE600 are targeted towards audiophones, though engineering geeks are bound to be fascinated by Sennheiser’s dogmatic insistence on the superiority of a single-driver arrangement, their extra attention to tuning across both ears, and their remarkable new 3D printed exterior.

But more importantly, those who love to hear music in the best possible quality will find that these are impressively small in-ear headphones with undoubtedly big, detailed and clear sound – and are well worth their asking price.

Sennheiser IE600 review: price & release date

The Sennheiser IE600 in-ear monitors launched in March 2022, and in the United Kingdom you’ll need to part with £599 to get hold of a pair. In the United States they’ll set you back $699, and in Australia they sell for AU$1,199.

You don’t really need me to tell you that’s quite a lot of money for in-ear monitors of any type, let alone IEMs with a cable attached. So if they’re going to make any sense at all, the IE600 are going to have to make about as strong a case for wired mobile listening as it’s possible to imagine.

Sennheiser IE600 review: features & what's new

There's not so much anything 'new' to talk about in these headphones, but there is something unusual. While many alternative brands will augment a dynamic driver with a balanced armature or two when specifying their top-end in-ear monitors – often for no other reason than it’s ‘the done thing’ – Sennheiser argues that a single full-range dynamic driver is inherently more effective. As long as it’s implemented properly, of course. And it looks to have justification for that claim here.

To that end, Sennheiser is very proud of its manufacturing processes where this component is concerned, as well it might be. The channel-matching between left and right earbud transducers is claimed to be the most accurate in the industry.

It uses pair of painstakingly developed 7mm extra wide-range ‘TrueResponse’ transducers to deliver the sound.

You get two cables in the box: one with a 3.5mm jack, and one with a 4.4mm plug.

Sennheiser IE600 review: sound quality

It seems only right and proper that the sort of rigorous attention to detail Sennheiser has paid in the manufacturing of the IE600 should result in an equally detailed sound – so it’s both a pleasure and a mild relief to confirm it is indeed the case.

No detail is too minor, too fleeting, too deep in the mix for the IE600 to overlook. Without being in any way drily analytical or tediously forensic about it, the Sennheiser locate and deliver every scrap of information in a recording. They give it proper context and weight, and they do so without ever losing sight of the fact that it’s the entirety of a performance, its unity and coherence, that’s the most important thing. 

And in most other respects, the IE600 are very nearly as impressive – that’s to say, they’re very impressive indeed. 

The bottom of the frequency range is substantial, properly controlled and organised, and punches hard. There is, of course, an absolute stack of detail regarding texture attached to bass sounds – but equally important is the speed and momentum with which the Sennheiser deliver it. It’s a similar story in the midrange, inasmuch as singers get to showcase their technique, their power and their emotion, but without ever sounding estranged or remote from the rest of the recording.

Dynamic potency is never in question here. Of course, the borderline-obsessive way the IE600 dish the details means that no hint of harmonic variation eludes them, but they’re equally adept when the quiet middle eight gives way to the almighty charge into the last chorus. 

They’re every bit as eloquent when dealing with the big gestures as they are the fine details – and they allow it all to take place on a large, properly defined and thoroughly organised soundstage. Even when the going gets complex or hectic, locating specific elements of a recording is no trouble whatsoever. 

If there is a down-side to the way the IE600 perform, then it’s pretty mild and hardly detracts from the overall quality of their performance. But still, at the top of the frequency range there’s a little suggestion of overexuberance – in the wrong circumstances (unsympathetic source player, highly trebly music) it can jar just a little. There’s nothing wrong with some crunch and attack at the top end, but the IE600 sometimes get a rather dangerous glint in their eye.

Sennheiser IE600 review: design & usability

There may not be much of them, but what there is of the IE600 has been very carefully designed and constructed by a company seemingly uninterested in cutting any corners whatsoever.

The earbuds themselves are 3D printed using a material called ZR01 amorphous zirconium. Yes, it’s a bit of a mouthful – but what’s important to know is that it’s three times as hard, and three times as resistant to bending, as regular high-performance steel. Sennheiser has treated its surface so it resists corrosion or scratching, and on the inside has found space for an acoustic back chamber and a couple of dual resonator chambers at the nozzle. These technologies are designed to deal with masking resonances, allowing the IE600 to sound precise and neutral. 

The earbuds join their cable via gold-plated MMCX connectors, which means you can, in theory, swap out either or both of the two cables Sennheiser provides (one terminating in a 3.5mm jack, the other in a 4.4mm equivalent) for something different. It is a bold listener who chooses to do so, though – apart from a willingness to transmit a bit of thump when it’s knocked, the cables here are extremely high-performance. And they have integrated flexible ear-hooks too, which is usefully where comfort is concerned.

Comfort is also provided by the selection of eartips in the packaging: there are ‘S’,’M’ and ‘L’ pairs in silicone and in memory foam. Find your nearest fit, use the old ‘push and twist;’ method of positioning the earbuds, and they’ll stay comfy and secure for hour after hour.

Sennheiser IE600 review: verdict

‘Wired’ beats ‘wireless’ every time, all things being equal – but when you’re asking this much for wired in-ear monitors, ‘beat’ isn’t quite enough. Happily, the Sennheiser IE600 don’t so much ‘beat’ the best true wireless in-ears around ‘wipe the floor’ with them. 

So if your digital audio player is similarly talented – be sure to look at our list of the best headphones DACs to pair with them – the IE600 will take your mobile listening experience to a whole other level.

Sennheiser IE600 review: also consider

They’re made to look a bit of a bargain by the Sennheiser IE600, and at ‘only’ £449/$499 a pair, the Shure AONIC 5 wired in-ear monitors have plenty to recommend them. Shure is just as venerable a name as Sennheiser where products like this are concerned, and while the AONIC 5 don’t have quite the same bee in their bonnet regarding detail retrieval as the IE600, they’re every bit as listenable, every bit as convincing and every bit as accomplished. They’re not as accommodating as the Sennheisers where ropey recording or poor source players are concerned, mind you.