PSB M4U 9 Wireless Noise Cancellation Headphone - Black

PSB's Graphene Driver Comes to Its Wireless Headphone Lineup

The PSB M4U 9 is a closed-back wireless headphone built around a graphene-infused 40mm driver, a material exclusive to this model in PSB's headphone lineup. Active Noise Cancellation, RoomFeel tuning, and Bluetooth with aptX Adaptive round out the package.

A three-position switch covers ANC, Active (non-ANC electronics on), and fully Passive listening, so the M4U 9 keeps working as a standard wired headphone even with a completely dead battery.

The free PSB Headphones app unlocks Audiodo Personal Sound calibration, tuning the headphone's response to your own hearing profile — a genuinely useful feature, though it does mean the app isn't optional if you want the full experience.

Where the Graphene Driver Earns Its Keep

A Graphene-Infused Driver, Exclusive to the M4U 9

Graphene is exceptionally light and stiff compared with a conventional cone material, letting the 40mm driver move faster and resist breakup at higher output, running at 32 ohms passive impedance for easy drive from a phone or laptop.

RoomFeel technology adjusts the frequency response to compensate for the artificial bass buildup that closed-back designs create sitting directly against the ear, aiming for a more open, genuinely speaker-like presentation instead.

Three-Position Switch: ANC, Active, or Fully Passive

Flip to ANC for maximum quiet, Active for the onboard amplifier without noise cancellation, or Passive to run the M4U 9 as a completely battery-free wired headphone through its 3.5mm or USB-C connection.

Bluetooth pairing supports AAC and aptX Adaptive codecs, and the rechargeable battery delivers up to 25 hours in Active mode or 18 hours with ANC engaged, matching PSB's own published M4U 8 MkII figures.

Who Is the PSB M4U 9 Best For?

• You want PSB's newest driver technology: the graphene-infused driver is exclusive to the M4U 9 in PSB's current headphone lineup
• You want a headphone tuned to your own hearing: Audiodo Personal Sound calibration through the free PSB app adjusts the response specifically for you
• You want a true battery-free fallback: the Passive switch position works over a wired connection with zero power at all
• You want the newer aptX Adaptive codec: a more recent standard than the aptX HD used on PSB's M4U 8 MkII
• You want PSB's RoomFeel tuning wirelessly — speaker-derived voicing with active noise cancellation and aptX Adaptive

How Does It Connect to Your System?

Pair over Bluetooth from a phone, tablet, or computer using AAC or aptX Adaptive, or connect the included 3.5mm or USB-C cable directly for a wired connection in either Active or Passive mode.

Download the free PSB Headphones app to run Audiodo Personal Sound calibration and adjust RoomFeel settings — the headphone plays music without it, but the personalization features specifically require it.

Pairs Well With

What finishes the system around a PSB M4U 9:

• Headphone amplifiers — for driving the M4U 9 in passive mode from a home system
• Headphone cables — a spare or longer cable for wired listening
• Headphone stands — a proper resting spot between listening sessions
• Headphone accessories — replacement earpads keep the M4U 9 fresh over years of use

Frequently Asked Questions

What does the graphene driver actually do?

Graphene is lighter and stiffer than a conventional driver cone material, letting the diaphragm move faster and resist breakup at higher volume levels.

Do I need the PSB app to use these headphones?

Not for basic playback. The app is required specifically for Audiodo Personal Sound calibration and RoomFeel adjustments, PSB's two signature personalization features.

Does the M4U 9 work with a dead battery?

Yes, in the Passive switch position. Connect a 3.5mm or USB-C cable and it runs as a standard wired headphone with zero power required.

How long does the battery last?

Up to 25 hours in Active mode, or 18 hours with ANC engaged, the same figures PSB specifies for the M4U 8 MkII.

How is this different from the M4U 8 MkII?

The M4U 9 uses a graphene-infused driver and supports aptX Adaptive instead of aptX HD; the M4U 8 MkII shares the same battery life and connection options at a lighter weight.

See It in Action

RonOnTech pits the M4U 9 head-to-head against DALI's iO-8 in a direct comparison:

PSB Speakers presents PSB M4U 9 Review: Next‑Level Noise Cancelling & Audiophile Clarity.

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