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Audio-Technica ATH-CKX9iS SonicFuel in-ear headphones review

The ATH-CKX9iS headphones are the top in-ear model in Audio-Technica’s SonicFuel range. The headset aims to offer superior comfort and sound quality in today’s highly saturated, ultra-competitive sub-$100 price range.

Established in Tokyo in 1962, Audio-Technica is one of the most storied designers and manufacturers of audio equipment. The company’s headphones’ lineup ranges from sub-$20 earbuds, all the way to $1,000+ closed-back over-ear, audiophile-centric headphones.

Retail package

The ATH-CKX9iS headset ships in a rich retail package. Inside it you will find the headphones, a hard carrying case, and replacement ear tips and C-tips, including a pair of Comply foam ones.

The retail package has all the goods

There’s nothing missing in the headphones’ retail box as far as additional accessories go. You are fully covered.

Design and build quality

The design of the Audio Technica ATH-CKX9iS in-ear headset is utilitarian. In line with their rich heritage, the headphones’ appearance leaves no doubt about their serious aspirations – from the large housings, all the way to the ergonomically shaped ear tips.

Audio-Technica ATH-CKX9iS live photos

There are two color schemes available – grey with blue and black accents and all-black. They grey color unit I tested is clearly more eye-catching thanks to its dual-color flat cable and metallic finish of the earbuds.

Build quality is outstanding. The headset, its L-shaped audio jack, and the remote control are all made from high-quality, solid-feeling plastic.

The 1.2m flat cable has thick rubberized cover, so it can take plenty of abuse too. To top things off, the ATH-CKX9iS headphones come with two-year warranty from Audio Technica – a truly rare sight in their price category.


Despite its large footprint, the ATH-CKX9iS headset is extremely light at 10 grams without the cord. The low weight, combined with the ergonomically shaped in ear tips and the C-tips makes the headphones comfortable to wear during long stretches of time.

The remote features a single click button and a sliding volume rocker which works on any device it is connected to. Both are easy to access and operate on the go.


The Audio Technica ATH-CKX9iS headphones feature a 13.5mm audio driver. The latter is a lot larger than usual – the norm in this price range is usually between 9 and 10mm.

Frequency response of the driver ranges between 5 and 25,000 Hz. Sensitivity and impedance are 104dB and 32 Ohms respectively. The maximum input power is 20 mW.

The real-life sonic experience which the ATH-CKX9iS delivers impresses with its sheer dimension thanks to the larger than usual audio drivers. Sub-$100 in-ear headphones are generally not expected to sound as competent as the ATH-CKX9iS.

Bass is as deep as the 5 Hz bottom of the frequency response range suggests, and defines the character of the headphones in a good way. It sounds pleasantly natural even at low volume, once again thanks to the large audio drivers on tap.

The high-range is clear, well-defined, and lacking the harshness which some of the rivals display. The mid-range, while not perfect, falls in line with the expectations which the price tag of the ATH-CKX9iS headset carries – sound monitors these headphones are not. Neither are any sub-$100 earbuds however.

The phone calls’ audio quality was good. There’s nothing to frown at on this instance.

Final word

The Audio Technica ATH-CKX9iS headphones are easily among the best in-ear offerings available for the money at the moment. They will not win any beauty contests, but will certainly make up for it by bringing great sound, superb build quality, and lengthy warranty coverage to go with Audio Technica’s brand cachet.

The Audio Technica ATH-CKX9iS is priced at $99.95. I recommend the headset to anyone looking to upgrade his/her bundled smartphone headphones with the budget to do so.

You can pick at pair of the Audio Technica ATH-CKX9iS in the company’s online store over here.


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