Headphone Reviews

It used to be on my commute that I'd see my fellow subway riders listening to music on their iPods with headphones from Beats, Bose, Sennheiser, Sony—and even, occasionally, from Grado. These days, however, iPhones and Android smartphones are ubiquitous, and while I still sometimes see a pair of Beats, many travelers now wear Bluetooth-connected Apple AirPods. I haven't bought a pair of AirPods, so I don't know how they sound, but at $159, I suspect they don't compete with "legitimate" headphones. Even so, I wondered if convenience trumps sound quality when it comes to listening on the move. So when I saw that Shure had introduced a Bluetooth adapter for their line of sound-isolating in-ear monitors, I asked for a review sample (footnote 1).

The Bluetooth 5.0 Earphone Communication Cable ($149) offers support for the aptX, aptX HD, aptX Low Latency, AAC, and SBC audio codecs. Two short cables that spring from a small Bluetooth receiver and DAC module connect to the two earpieces. An inline remote with microphone control is mounted halfway up one of the earpiece wires, and a hinged cover on the module's base opens to reveal a USB-B Micro jack to charge the battery. Up to 10 hours of playing time is said to be possible on one charge (compared with the AirPod's five hours), with up to 350 hours of standby time.

As well as the Bluetooth 5.0, Shure sent me a pair of their SE535 in-ear headphones ($449). The triple-driver "acoustical engine" of the SE535, which was introduced in 2011, is almost the same as that used in Shure's earlier SE530, which was favorably reviewed by the late Wes Phillips in December 2007. (Shure says that the SE535 has a refined acoustic network in the front section of the earphone, which results in a "slight increase in clarity and a bit wider soundstage" (footnote 2).

The Bluetooth 5.0 cables plug into the Shure IEM earpieces, so using the Bluetooth 5.0 was simply a matter of replacing the SE535's regular cables with those of the Bluetooth adapter. Pressing and holding the raised center button on the inline remote turns the Bluetooth module on or off. (The two other buttons adjust volume up and down.) To pair the Shure adapter with a Bluetooth data source such as a smartphone, you hold down the center button while the source searches for Bluetooth devices. Pairing is automatic; the Shure then appears in the smartphone's Bluetooth menu as "Shure BT2."

Regular readers will be aware that I'm a bit sniffy about Bluetooth-connected audio products, because of the necessary use of a lossy codec to reduce the data rate to match that of the wireless link. Qualcomm's aptX is used in Android phones and desktop Macs but not in Apple's iOS devices, which offer Apple's AAC as their Bluetooth audio codec in place of the earlier, sonically compromised SBC codec. The aptX codec trades off low-level resolution in favor of preserving a random noise floor, and is widely regarded as sounding better than AAC, which appears to try to preserve resolution at the expense of noise-floor modulation and the introduction of enharmonic spuriae (footnote 3).

So how did it sound? While the Shure SE535 IEMs still sounded better when driven directly by my iPhone 6S—though not equaling Shure's electrostatic KSE1200SYS in transparency and low-frequency weight—their Bluetooth-connected, AAC-encoded sound wasn't as inferior as I'd expected. The orchestral climaxes in George Vatchnadze's performance of Rachmaninoff's Piano Concerto 2, with Jansug Kakhidze conducting the Tbilisi Symphony Orchestra (16/44.1 ALAC rip from CD, Sony Classical Infinity Digital 62294, converted on the fly to AAC), were more congested, but much of the time this wasn't an issue.

Hard-driving rock wasn't served quite as well as classical music. My go-to track for headphone testing is "Bullet with Butterfly Wings," from the Smashing Pumpkins' Greatest Hits: Rotten Apples (256kbps MP3 file, Virgin). Due to what I believe is the cascading of codecs—MP3 converted to PCM, then converted to AAC for transmission—this track was reproduced with appropriate force but with an increase in midrange congestion compared with the direct connection from the iPhone.

Even so, if you already own a pair of Shure's in-ear monitors, the Bluetooth 5.0 Earphone Communication Cable will eliminate the wires from your subway ride with only a small penalty in sound quality.

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Footnote 1: Manufacturer: Shure Inc., 5800 W. Touhy Avenue, Niles, IL 60714-4608. Tel: (800) 257-4873, (847) 600-2000. Fax: (847) 600-1212. Web: www.shure.com/americas.

Footnote 2: In May 2011, for our InnerFidelity website, Tyll Hertsens examined the technology used in Shure's SE line, including the SE535.

Footnote 3: See my measurements accompanying Sam Tellig's review of Arcam's rBlink Bluetooth DAC in December 2013.