With this big shift over the past decade to wireless headphones from the traditional kind, audiophiles have been dealt the biggest blow in the name of practicality. Bluetooth connectivity simply makes it more difficult to emulate your music the way the artists and producers intended you to. Larger drivers on over-ear monitors might feel like worthy compromise, but their more stowable in-ear counterparts have never really made it their business to give the listener lossless audio quality, until now.
Leave it to Astell&Kern to find the perfect partner for solving this problem. The South Korean digital audio pioneer has teamed up with 64 Audio — the American IEM specialists who’ve been pushing boundaries since their 1964 Ears days — to create the XIO, a $3,000 pair of in-ear monitors that houses ten drivers per side and enough proprietary tech to make any audiophile drool.
Engineering at the Extremes
Ten drivers in an earphone might sound excessive until you understand how 64 Audio has orchestrated this symphony. Each XIO monitor features two dual-dynamic bass drivers working in what they call a “TRUE ISOBARIC” configuration. Essentially, this means two drivers are perfectly synchronized in an acoustically neutral chamber for bass that hits deeper than conventional IEMs can manage. Six balanced armature drivers handle the midrange, with another dedicated to upper-mids, while a direct-radiating tia (Tubeless In-Ear Audio) driver takes care of the highs.
The 4-way passive crossover ensures each frequency band transitions seamlessly, creating what both companies describe as a “spacious, realistic soundstage.” The tia driver alone is the result of years of 64 Audio’s research, eliminating traditional sound tubes entirely and reducing resonance and distortion while delivering highs that feel almost weightless. Likewise, the LID (Linear Impedance Design) technology compensates for driver resistance variations, meaning your XIO will sound consistent whether you’re plugging into an Astell&Kern DAP or your laptop.
Fans of 64 Audio will be happy to discover that they’ve integrated their patented apex system, which naturally releases pressure from your sealed ear canal while maintaining isolation. This can be a real problem with in-ear monitors, especially after hours-worth of listening.
Precision Manufacturing Meets Audio Art
For the XIO, Astell&Kern opted for 904L stainless steel, which is significantly harder to machine than conventional steel. Each shell is precision-milled before receiving a black Diamond-Like Carbon coating for a matte black aesthetic. Meanwhile, the faceplate carries Astell&Kern’s design DNA, creating depth through carefully engineered shading and reflections.
And since these are wired earbuds, they come with silver-plated UP-OCC copper Litz cables featuring a four-core cross-braided design that maintains just 0.29Ω impedance and excellent noise shielding. At the end there’s a 4.4mm balanced connector (Astell&Kern’s preference for their high-end DAPs) though you’ll likely want to grab adapters for other sources.
Spec Sheet
Model: XIO
Drivers: 10-driver hybrid system (2 dual-dynamic bass, 6 mid-range BA, 1 upper-mid BA, 1 tia high-frequency)
Crossover: 4-way passive
Frequency Response: 5Hz-22kHz
Material: 904L stainless steel with DLC coating
Cable: 4.4mm silver-plated UP-OCC copper Litz
Made in: USA
Pricing & Availability
The Astell&Kern x 64 Audio XIO will be available through authorized retailers starting in August, and priced at $3,000. Each pair includes premium leather carrying case, multiple ear tip options, cleaning accessories, and interchangeable apex modules for fine-tuning the sound signature to your preferences.
Recap
Astell&Kern x 64 Audio XIO Earbuds
Astell&Kern just made possibly the best in-ear monitors on the market with the help of 64 Audio’s tech and lossless audio quality.
