IE 600
Here's the second of my reviews of my collection, the quite popular IE 600. I bought my pair at launch in early 2022, for the full MSRP of $800, as a more comfortable alternative to the IER-Z1R that I daily drove at the time. While comfort was certainly a massive improvement, there were a few significant drawbacks. Note that this review was done with the Final Audio E Type tips. While I generally try to use stock tips, that was impossible in this case. No pictures again, cause I need to take better photos.
Build & Comfort
The actual
build portion of the IE 600 is absolutely superb - it's small, comfortable, and clearly built to last. Even the proprietary MMCX was designed with durability in mind, although at massive cost to replaceability. The zirconium alloy shells, being solid, strong, and textured, feel practically indestructible. In the ~1.5 years I've owned my pair, there's not been a single scratch or blemish on them. And while the nozzle is plastic, Sennheiser's history with plastic suggests there is nothing to worry about there.
In isolation, the IE 600 is extremely comfortable being one of the smallest high-end IEMs out there. The shape also lends itself well to setting deep in your ear, without being an overly-deep insertion. The nozzle, while being a little wider than many other IEMs, also doesn't go far enough in to be an issue. The actual isolation isn't incredible though, which leads us into the most serious problem with the IE 600...
A solid 9/10. Would be 10 if the isolation was better.
The Accessories (and related issues)
The IE 600, with little exception, comes with some of the worst accessories I've ever seen in an IEM. And not just for expensive HiFi, but in general. Seriously, ~$30 earbuds I bought from JLabs 10+ years ago had better accessories. The only thing in recent memory that was equally bad was the BL03, an IEM that goes for 1/20th what I paid for the IE 600. This has been an issue on every Sennheiser IEM I've owned, since the IE 80, and it's sad to see that they've failed miserably to rectify it after all these years.
Now, those are some awfully harsh words, but words I fully intend to back up. Let's start with the ear tips. The IE 600 comes with a nice selection of foam and silicone tips. The foams are a collaboration with Comply, while the silicones are Sennheiser's own in-house design, and both types have a thin filter attached – a nice way to keep earwax/dust out of the IEMs.
This is where the problems begin. The filter, thin as it may seem, is an essential part of the IE 600's tuning and keeps the treble from being piercing and sibilant. Meanwhile, the foam ear tips will blunt the micro details while in typical Comply fashion also degrade in the span of just a month. Never mind how you'll only have 1 pair in your size,
and they're not even as comfortable as regular Comply tips.
The silicone tips however, are somehow even worse. It is almost impossible for me (and it seems most other people) to get a consistent seal with them. They're way too thin and thus when squished will collapse instead of filling your ear canal like normal silicone tips. And seeing as how human ear canals aren't perfectly cylindrical, this will consistently happen unless you're extremely careful with the insertion depth. I don’t think I ever once got them to seal perfectly in both ears and actually stay sealed.
The solution might seem obvious - 3rd party ear tips! But this is when that filter comes back to haunt us. Without it, the already spicy treble will be sibilant and piercing on many of the 3rd party tips out there. I've settled on the Final Audio E types, the best of a bunch of poor choices, but your results may vary. Do let me know if you’ve found something that works better than the E Types though, I’m always open to improvements (just not so much paying for the experimentation).
This isn't even mentioning the stock cable(s), which come in 3.5mm and 4.4mm balanced. These cables are absolutely atrocious. They're poorly behaved, prone to tangling, uncomfortable, and even worse,
microphonic. The shapable (yet non-removable) ear hooks are a huge part of the problem here. It's difficult enough to shape them properly for your ears, until they change shape the moment you take the IE 600 off or wrap them for storage. The cables and ear hooks will also pull on the shells, breaking the seal on the ear tips.
But it gets even worse. The MMCX connector on the IE 600 is actually proprietary, with an extra lip that means regular MMCX connectors will be too short to make a proper connection. It might be better for durability, but this gave me hell when trying to find 3rd party replacements. It's a little better now that they've been on the market for a while, but most compatible cables will either be more expensive, or you'll need to take your chances with random AliExpress cables.
It's almost like every product Sennheiser makes has to have a proprietary cable or they won't approve it. HD600 2-pin, HD800 janky thing, IE80's weird semi-circle 2 pin, now the IE_00 line and their recessed MMCX connectors.
I find it absolutely mind boggling that Sennheiser, a huge powerhouse in the audio industry, would somehow let an $800 ($1200 if you consider that the IE 900 comes with the same accessories) product leave the lab with such terrible tips and cables. Especially when the tips and fit directly impact the sound so significantly.
The included carrying case is better, being a nice zip up hard shell. It's a little on the small side, however, and would only hold the IE 600 and your choice of USB C dongle. Anything larger and you'd run into difficulty zipping it up and possibly crush a connector. Not terrible, just not ideal.
0/10 - I'd give it a -2/10 if the case wasn't a little useful. It's like nobody even tried to use them before shipping them out.
Anyways, enough griping about the accessories, here's:
Sound Quality
Overall, the IE 600 is a high performer, with a V-shape sound that extends well into both ends of the frequency response. While it's not my favorite type of sound, the IE 600 does what it does well
really well.
Bass
The bass digs deep into the subbass, with clear impacts and good delineation from the mid-bass and mid-range. There is no bloat or muddiness either. Overall, the IE 600 has very high-quality bass, and is relatively bassy, but keeps away from being warm or laid back. On my standard bass test track, Free Tibet (Vini Vici Remix), the IE 600 truly shows this off. At 1:40, when the bass kicks in, you can clearly feel each individual bass hit and subbass fluctuation. There’s really not much to say here, it’s just really great bass.
10/10
Mids
The mids however are a little more recessed than I would like, even more so depending on the singer’s voice. Deeper male voices generally sound more natural, although still more pulled back than I’d like, with good rumble and gravel where expected. Brighter voices, especially brighter female vocals, however, show some issues. They tend to be a little hollow on the lower end, due to the mid-range scoop on the IE 600’s FR. On the higher end, the voices will be a little too shrill and piercing at times. Combined, this creates a sense of unevenness in the vocals – you can sometimes hear voices exhibit this as a singer moves up the frequency range.
7/10
Treble
Finally, the treble is a little too sharp and piercing, depending on the ear tips that you’re using. This is where the horrible stock tips peek their ugly head again – without the filter in the stock tips to pull back the high end, the treble will be unpleasant and piercing especially with wide-bore tips. This combines with the pulled-back mids to make certain voices and instruments sounds hollow and flat or have an icy edge. However, this is also very tip and insertion depth dependent, so your mileage may vary. It’s not all bad though; the IE 600 extends well into the high end and sparkles where expected and prevents anything from sounding lifeless or dull. And despite being piercing at times, the treble is never quite sibilant.
7/10 to 9/10 depending on your sensitivity to treble and the tips you use.
Soundstage and Technicalities
Perhaps a result of the emphasized treble, the IE 600 is a very detailed and well separated IEM. There’s never any sensation of blurring, muddiness, or losing track of instruments in busy sections of songs. The attack on all parts of the FR is clean and fast, with a clear delineation note to note. Microdetails as well are clear and present.
In a similar vein, the IE 600 also does a great job with instrument separation and positioning. This means that everything is clearly around you in a 3D space and can be picked out just by focusing a little on its location. And while it also manages to create layers of different pieces of the track, the IE 600 doesn’t quite manage to give them depth. Certain things will sound more forward than others, but none of it will quite sound quite distant or spacious. Especially in the central channel where things like vocals can take on an “inside your head” sensation. This is most obvious with female vocals.
The FR also doesn’t lend itself well to natural timbre, although not egregiously unnatural and strange. Instead, vocals may sound a little too grainy, hollow, or sharp depending on their range. For example, on Miwa’s ‘Hikarie – From THE FIRST TAKE’, the singer’s voice sounds almost hoarse or with a sore throat instead of a more natural texture. This holds true for most instruments and voices, although it varies for each; IE 600 is most natural with deep male vocals. This is another aspect that I feel was remedied by the filter in the stock tips. Too bad they’re absolutely unusable.
Again depends on your ear tips. Between a 6/10 and an 8/10.
Conclusion
As you can see, I’m quite a bit more negative on the IE 600 than many other reviewers here are. However, I feel that once you factor in the atrocious accessories, the IE 600 is only left with its comfort and bass as standout qualities. And those are absolutely incredible strengths that are weighed down by so many issues (most of which are indirect results of the accessories). Perhaps if you can find the perfect 3rd party cable and tips the calculus changes, but I easily went $200 in on accessories before finding a combination that was “good enough” (Hart Audio NK + Final E Types). For my total cost (~$1k USD), there are definitely better options out there that should be considered before the IE 600.
That said I'd love to know if there is an IEM that stands out in the same price range, that doesn't have to be leveled up with cables and other accessories. I try to keep my mind open while searching for audio nirvana and wine!