Penta Balanced Armature System
For clean high notes, natural tones, and the pure emotion behind every performance, the IER-M9 has a Penta BA system including a magnesium super tweeter. Sony's original T-shaped Balanced Armature directly drives the diaphragm for more linear motion, and clean, faithful high notes.

Magnesium Diaphragm Super Tweeter
The IER-M9 super tweeter diaphragm is made of lightweight and rigid magnesium alloy to deliver the fast dynamic transient of performance. The unique BA unit design also benefits from extremely low resonance thanks to high internal loss. Internal wiring is upgraded with a new silver-coated copper voice coil and gold-plated terminals, faithfully reproducing sound without sacrificing even micro signals so pitch, harmonics, and emotion are portrayed.

Audio grade Film Capacitor
Our custom audio grade film capacitor in the cross-over circuit delivers much lower distortion. The audio grade capacitor of the IER-M9 delivers fine detail sound. Plus, audio grade solder also helps minimize any loss in signal path.

Integrated Magnesium Inner Housing
A highly rigid housing keeps the BA units firmly in place, helping to eliminate vibration and keeping sound clear without losing even the most minute detail in your sound.

Optimized Sound Path
A wide and short sound path made of magnesium alloy reduces frequency peaks and dips, to give a monitor sound you can rely on for critical listening accuracy. A 0.17" standard balanced connection cable separates left and right sound signals completely, which minimizes cross-talk that results in sound deterioration.

Silver-Coated OFC
Silver-coated, oxygen-free copper wire minimizes resistance and signal-transmission loss. The result is less sound degradation, finer detail, and smoother treble sounds. Vibration is absorbed by the silk braid cable insulator to minimize rustling when the cord is touched. A gold-plated plug with non-magnetic undercoat preserves signal purity.

13 Variations of Earbuds
Six triple comfort and seven hybrid silicon earbuds let you find a snug fit for all kinds of ear shape. Combining hard silicone rubber and specially developed formed silicone, they perfectly match sound with stability and are comfortable to wear for long periods of time.