Sennheiser MM 400-X Headphone Review

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The Sennheiser MM 400-X is a wireless headphone powered by stereo A2DP Bluetooth technology. It allows wireless music enjoyment wherever you are, whatever you’re doing and whenever you want. The headphone has a supra-aural and fine design that produces an amazing surround sound. It includes a direct cable for an onboard listening session.

Design and Build

The Sennheiser MM 400-X is a lightweight headphone with soft featherweight cushioned ear pads. It makes them so easy to use even when used for an extended period of time. The headphone is designed to be foldable so they can be easily stored in its carrying case when you’re traveling.

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Sennheiser MM 400-X Wireless Bluetooth Travel Headphones
  • Allows wireless freedom with Bluetooth 2.1 advanced A2DP profile
  • Invisible microphone for crystal clear conversation
  • Direct cable option for use on airplanes
  • Collapsible construction for easy portability
  • Two year warranty

Sound Quality

The Sennheiser MM 400-X boasts of an apt-X codec for a full, wealthy and crisp CD-quality sound with a DuoFol transducer system.

It produces a vibrant sound, superb bass and has explicit details that every music lover can enjoy.

The frequency response is 15 – 22000 Hz and a sound pressure level of 107 dB.

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Bluetooth Transmission

The Sennheiser MM 400-X uses Bluetooth 2.0 + EDR technology to pair it to Bluetooth-enabled devices flawlessly. It supports the A2DP, AVRCP, HSP and HFP Bluetooth profiles. It can store up to 8 Bluetooth devices.



The Sennheiser MM 400-X is operated using a 250 mAh lithium-polymer rechargeable battery. This headphone has a typical operating time of around 10 hours. If the battery drains, you can charge it in 3 hours using the micro-USB cable included in the package. You can optionally purchase a spare battery. In case the battery drains and you’re outside, you can use the 3.5mm jack cable for wall charging.

In-flight Session

The Sennheiser MM 400-X has included a 3.5mm double mono jack plug in-flight adapter. The user can use this on commercial flights since some of the airlines forbid Bluetooth connectivity while onboard.

Microphone and Controls

The Sennheiser MM 400-X has straightforward and convenient controls placed on the right earpiece. You can effortlessly switch it on/off, play/pause tracks, regulate the volume and skip tracks without removing the headphone. There’s also a Bluetooth button in the bottom part of the right earpiece to quickly switch the Bluetooth connectivity on/off. It also serves as a button for redial, mute and scanning tracks.

The Sennheiser MM 400-X built-in invisible microphone makes it stress-free when answering incoming calls with clarity and flawlessness.

More Features

The Sennheiser MM 400-X comes with:

  • USB wall charger
  • USB charging cable
  • Audio cable
  • In-flight adapters
  • Carry case


I love to travel, and this headphone has got to be the perfect pair for my traveling times. The in-flight adapters are helpful because they’ve forbidden Bluetooth on some airplanes. The sound quality is just fantastic, and it’s so lightweight that I almost forget I am wearing a headphone. Great job Sennheiser!

Product Comparison

mm 400-x vs beats


  • DimensionDimension
  • WeightWeight
  • BatteryBattery
  • Battery LifeBattery Life
  • CableCable
  • Charging TimeCharging Time
  • ManufacturerManufacturer
  • OriginOrigin
  • PricePrice

  • Dimension7.5 x 3.3 x 7.9 Inches
  • Weight1.3 Pounds
  • Battery250 mAh Lithium-polymer Rechargeable Battery
  • Battery LifeOn use: 10 hours
  • CableIncluded (0.8m)
  • Charging Time3 hours
  • ManufacturerSennheiser
  • OriginGermany
  • Price$$$

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Sennheiser MM 400-X Headphone













  • Excellent battery life, and you can replace it with a spare one (to be bought separately)
  • Foldable, makes it easy for storage
  • Direct cable option that you can use in airplanes

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