The 109 PRO features a 50mm dynamic driver with a Dual-Composite Diaphragm made of Beryllium-coated polymer and cellulose-carbon fiber composite. The driver also includes a copper-zinc alloy stabilizer ring to reduce distortion, a neodymium magnet, and a copper coil encased in a high precision aluminum frame. The W-shaped dome is made of a carbon fiber enforced cellulose composite, while the ultra-thin torus surrounding the dome is composed of Beryllium-coated semicrystalline polymer. These materials and design elements contribute to the headphone's ability to reproduce high-frequencies with incredible detail, clarity, and definition, while minimizing resonances and distortion.
The 109 PRO features an open-back design that aims to provide vivid and exciting sound, with emotionally engaging detail, clarity, and punch. The driver is exposed from both sides within the earcup, creating an open pattern for superior dynamics and imaging. The headphones are carefully positioned for an ideal anatomical fit, with velour cushions providing comfort and breathability to prevent sweat and overheating during long listening sessions. Additionally, the self-adjusting headband evenly distributes pressure for any head shape and size.