IER-M9 In-ear Monitor Headphones


Picture of IER-M9 In-ear Monitor Headphones
Images of IER-M9 In-ear Monitor Headphones
Images of IER-M9 In-ear Monitor Headphones
Images of IER-M9 In-ear Monitor Headphones


5x Balanced Armature (BA) units for optimal sound design

For clean high notes, rhythm, pitch and the pure emotion behind every nuanced performance, the IER-M9 has 5x Balanced Armature (BA) Driver Units, including a Magnesium alloy Super Tweeter. 

Sony's original design Balanced Armature (BA) Driver units 

The unique T-shaped Balanced Armature directly drives the diaphragm for a more linear motion and clean, faithful high notes.

Magnesium alloy super tweeter 

The IER-M9 super tweeter diaphragm is made of lightweight and rigid Magnesium alloy to deliver the responsiveness required for describing subtle music nuance. The unique BA unit design also benefits from extremely low resonance thanks to a high internal loss. Internal wiring is also upgraded, with a new silver-coated copper voice coil and gold-plated terminals, to faithfully reproduce sound without sacrificing even micro signals — so pitch, harmonics and emotion are portrayed.

Audio grade film capacitor for less distortion 

Sony's custom audio grade film capacitor in the cross-over circuit delivers much lower distortion. The audio grade capacitor of the IER-M9 In-ear headphones delivers fine, relaxed sound. Plus, audio grade solder also helps minimize any loss in signal path. 

Integrated Magnesium alloy inner housing 

The BA units are held firmly in an integrated, high-rigidity housing. This helps to eliminate vibration and keeps sound clear and clean without losing even a micro nuance of sound.

Optimized sound path

While standard BA in-ear monitors rely on a long and narrow flexible tube in their sound path, the BA drivers in the IER-M9 In-ear monitors use a wide and short sound path made of magnesium alloy. This reduces frequency peaks and dips, and gives the ideal frequency response to ensure a monitor sound you can rely on for critical listening accuracy.

Balanced connection available

The IER-M9 In-ear monitors come with a 4.4-mm standard balanced connection cable which separates left and right sound signals completely, unlike conventional headphone cables where both channels share a ground wire. This minimizes cross-talk and the resulting sound deterioration.

Silver-coated OFC 

Silver-coated oxygen-free copper cables minimize resistance and signal-transmission loss. The result is less sound degradation, finer detail and smoother treble sounds.

Natural silk thread and non-magnetic undercoat plug

The IER-M9 uses natural silk thread as a cable insulator. This natural fibre works as an absorber against vibration and prevents rustling or bumping noises when you touch the cord. The gold plating of the plug has a non-magnetic undercoat which transfers the signal, preserving subtle nuances.

Light, durable Magnesium outer housing

Own the stage and the moment with the light, durable Magnesium alloy outer housing of the IER-M9 In-ear headphones. Stable fit and durable against knocks or accidents.

Detachable cable

The cable is fully detachable so you can replace it if needed, or fine tune your monitor sound through a different cable.

Pre-formed ear hanger for ease and stability

The IER-M9 In-ear headphones stably fit your ears through the universally shaped ear hanger. With firm fit and optimal housing shape, each ear bud stays in the right position.

13 variation of ear buds

Our earbuds come in thirteen variations — six triple comfort and seven hybrid silicon. So you can 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.

Discover a new realm of musical expression, in the studio and on the stage with IER-M9 In-ear monitor headphones designed for musicians. With 5x unique Balanced Armature drivers from Sony, including Magnesium alloy diaphragms and gold-plated terminals, every musical nuance is authentically reproduced.
  • 5x Balanced Armature (BA) Driver Units

  • Magnesium alloy diaphragm super tweeter

  • Sony's original design BA Driver Units

  • Light and durable Magnesium alloy outer housing

  • Pre-formed ear hanger for stable fit

Driver Unit
Penta Balanced Armature
Frequency Response
5 Hz–40,000 Hz
Cord Length
Approx. 1.2 m, silver-coated OFC strands, ear hanger, L-shaped non-magnetic gold-plated stereo mini plug, Approx. 1.2 m, silver-coated OFC strands, ear hanger, L-shaped non-magnetic gold-plated balanced standard plug

What's in the Box

Triple Comfort ear buds: SS, S, MS, M, ML, L, Hybrid Silicone ear buds: SS, S, MS, M, ML, L, LL Clip Carrying case, Cable holder, Cleaning cloth, Cable clip

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