Compared to the other types of products we review, innovation in the headphone market can sometimes feel a little slow. Enthusiasts tend to buy, review, recommend, and re-review the same few benchmark headphones year after year. New headphones are often little more than refinements of their predecessors. As technology fans, we’re hungry for new experiences. That’s why we looked forward to reviewing Audeze’s new iSine10 ($399). The iSine10 is a planar magnetic in-ear headphone that provides, somewhat paradoxically, an open-back experience. Audeze calls them the “world’s first” — though there is some debate about this in the headphone community, it’s certainly the only such headphone in production today. This unique configuration makes the iSine10 difficult to review. Should it be compared to fullsize open-back headphones or isolating in-ear monitors? With no direct competitor, it’s up to Audeze to justify the iSine’s price, sound, and polarizing design.

iSine10’s packaging and included accessories got us off to an encouraging start. Included in the box are a ballistic nylon case, three sizes of wide-bore silicone tips, four plastic ear guides, and two sizes of silicone “Earlocks,” (developed in collaboration with tactical gear company Surefire). The display case doubles as way to securely store the headphones and wind the cables inside the carrying case — a nice touch for protection of an admittedly pricey portable. Unlike the original Sine, the iSine10 includes both analog and Lightning audio cables as part of the standard purchase. The cables are flat and unsleeved, which makes them resistant to tangling but also a bit unruly in use.

We had some minor issues with the iSine’s ergonomics. Where most in-ears are small, rounded, and seat inside the concha, these driver housings are large, hexagonal, and stick out from the head by a few millimeters. The iSine10 is surprisingly light, but its long sound channels give the driver housings leverage to pull downwards, out of the ear. Though there is an engineering reason for the length of the sound channels – they house conical wave guides designed to improve various characteristics of the iSine’s sound – we found that it was not practical to use the iSine10 without some kind of ear support. This is especially true when using the Cipher cable, due to the added weight of the pod which houses that DAC and amplifier.



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The included over-ear guides are the most secure way to wear the iSine10, but they didn’t work for us. The semi-rigid plastic hooks had just slightly too short of a rise and too steep of an angle relative to the iSine10’s housing to fit comfortably on our ears. We had better results with the flexible Earlocks – these were far more comfortable than the over-ear hooks, but we found that some regular cleaning was necessary to remove skin oils that made them slip out of the concha. Audeze includes two pairs of the plastic over-ear guides, but they’re the same size; from our perspective, it seems like a missed opportunity not to have included two different sizes. Getting the iSine10 to fit was a bit tricky during our testing, but we won’t call it a dealbreaker – this is not the first time we’ve had difficulty fitting an IEM; the comfort of any in-ear can depend on the user’s individual anatomy.

When fit properly, the iSine10 is a unique experience. The silicone tips do not isolate like a traditional IEM, but instead seem to “concentrate” sound in the ear. The open-back design lets plenty of ambient sound in, but also provides for a wider soundstage and better imaging than we’ve ever heard in an IEM. Sound leaks out of the back of the iSine10 as well – not as much as some over-ear open back headphones, but it’s undeniably audible when played at high volumes in quiet environments. Regardless of whether you think the iSine10’s sound signature is for you, we think that this miniaturized open-back experience alone is worth a test drive.

The iSine10’s sound signature is difficult to pin down because it sounds different, depending on whether the analog cable or the Cipher cable is used. We listened to this headphone in a wide range of configurations, including a powerful tube amp, desktop solid state amp, a portable solid state amp, directly out of the iPhone’s headphone adapter, and using the Cipher cable. We listened to the iSine10 alongside a wide range of other headphones, including dynamic drivers and planars, open-back and closed-back, and IEMs. We put them up against cheaper portables and flagship cans, including Audeze’s own LCD-2 and LCD-3. With all this context, we found that the iSine10 is at once two completely different headphones. Depending on what you use to drive them, the iSine10 can be an interesting headphone that falls a bit short of its price tag, or it can be comparable to some of the best headphones on the market.

Our first week with the iSine10 was spent almost exclusively with the analog cable. As a planar magnetic headphone, the iSine10 responds well to amplification, but may be too sensitive for the high gain setting on some amplifiers. Over analog, we heard a warm sound signature that was at best “relaxed” and at worst “veiled.” This is not to say that the iSine10 wasn’t technically competent – we heard great bass extension and punch with all of the open-back soundstage and imaging that we think makes this headphone unique. Still, the recessed treble presents a somewhat congested atmosphere even compared to the famously warm sound of the Audeze LCD-2. Not yet having heard the Cipher cable, it’s a sound that we adjusted to and came to enjoy; this warmth makes for easy, low-fatigue listening, even though it can’t match the no-compromise quality of the LCD-3.

If the iSine10 was “relaxed” over analog, it woke up with the Cipher Lightning cable. Like the Sine and EL-8 Ti, the Cipher cable drives the iSine10 substantially better than an iPhone headphone jack or the Lightning-to-3.5mm adapter. However, unlike its predecessors, the iSine’s Cipher cable presented a very different sound compared to the analog cable, even with amplification. All the best qualities of the analog sound remained, but the “veil” was lifted. A substantially boosted (or, no longer recessed) treble gives the effect of greater detail; this was drastic enough that we were initially concerned that there might be a nasty treble spike, but we soon found that this was just a more balanced sound signature than the dark presentation over analog. Having spent substantial time with both, we think that the Cipher cable is the best way to experience the iSine10.

What is the Cipher cable doing, and why? In our previous Audeze reviews we guessed that the better sound was simply due to more amplification, but Audeze has offered a more interesting explanation: the laws of physics make it impossible to design a headphone that sounds exactly as the designers intended in all situations. Even the most expensive headphones have peaks or dips in their sound that make them not ideal for some users. With the Cipher cable, however, Audeze can “bake in” DSP settings that can adjust the iSine10’s sound to the Audeze house sound. With DAC, DSP, and amplifier controlled, the Cipher cable can consistently output sound that matches Audeze’s original intent. With the Audeze app, users can further customize the sound.

The iSine10 is a headphone clearly made by engineers, not a marketing team. Its looks are polarizing and one size does not (yet) fit all, but every apparent oddity is explained by the technology Audeze developed for this headphone. The iSine10 is a success in that it delivers a new experience and makes the best out of the inconvenience Apple created by removing the headphone jack. Planar bass used to require a 100mm diaphragm; the iSine10 packs most of the experience into a case slightly larger than a quarter. Some enthusiasts attempt to emulate their home audio experience by attaching “portable” DACs and amplifiers to their phones with rubber bands; Audeze has shown that the same can be achieved by some tiny inline electronics in the headphone cable. We think that headphone enthusiasts value function over form, and we have no problem dishing out praise for innovation.

Innovative as it may be, the iSine10 is not a go-everywhere do-everything headphone. It’s fun to use outdoors, but does not isolate from ambient noise and may not stay in place unless without the over-ear guides. The iSine10 sounds great at home, but many will reach for fullsize cans for longer listening sessions. Perhaps the best case for the iSine10 is as a portable audiophile experience — it’s a punchy planar magnetic sensitive enough to be driven by a phone and small enough to carry in a pocket, though it requires the Cipher Lightning cable to sound its absolute best.

Our Rating

B Recommended

Company and Price

Company: Audeze

Model: iSine 10

Price: $399