Why Choose Crutchfield?
Great gear and expert advice
Our experts help you pick the ideal gear for your needs.Meet our advisors
Free tech support for the life of your gear.Read about our one-on-one expert help
You may return items that are complete and like new for any reason within 60 days.See the details of our return policy
Earn one point for every dollar you spend and use those points to save on future purchases.Get full details on Crutchfield Rewards
Deep discounts on car installation gear
We offer vehicle-specific installation instructions, dash kits, wiring harnesses, and speaker accessories at deeply discounted prices with car stereo and speaker purchases. Available for most vehicles.Learn more
Trusted since 1974
Our customers have trusted us with their business, and they’ve helped us win awards for our service.Check out our most recent awards
The manufacturer’s warranty always applies.See more details
Sennheiser MM 400-X
Bluetooth® stereo headset with aptX® high-fidelity wireless audio capability
Item # 143MM400X | MFR # 504511
This item is no longer available.
Our take on the Sennheiser MM 400-X by Crutchfield's Dave Bar
Bluetooth for wireless music and talk
Going somewhere? Don't forget your Sennheiser MM 400-X portable headphones. They're fantastic for enjoying your music and managing your phone calls without getting tangled up in cords. These headphones include built-in Bluetooth technology for a hassle-free wireless connection to compatible devices, such as many cell phones, laptop computers, tablets, and MP3 players. You can use the integrated volume, track skip, and call answer/end buttons built into the right earcup for convenient operation while your phone or music player remains safely in your pocket, purse, or backpack. The MM 400-X headphones even support the latest aptX technology a sophisticated audio circuit that delivers true high-fidelity stereo sound wirelessly over Bluetooth with aptX-enabled sources.
Great comfort, sound, and convenience
The MM 400-X's soft padded ear cushions and adjustable headband provide a comfortable fit for hours of relaxed listening, making these 'phones great to have on long trips. The headset's folding design makes for easy storage when you travel. Sennheiser's patented Duofol diaphragms provide detailed, crystal clear sound. And just in case you need it, Sennheiser includes a cable plus an airline adapter for a direct wired connection in situations where Bluetooth isn't permitted, or you want to make use of in-seat entertainment and other wired sound sources.
What's in the Box:
- MM 400-X Wireless headphones
- BA 370 PX Lithium-Polymer rechargeable battery pack (installed)
- Wall charging power supply
- US power plug adapter
- EU power plug adapter
- UK power plug adapter
- AU power plug adapter
- Airline adapter (single female 3.5mm-to-dual male 3.5mm)
- 50" USB charging cable (Type A USB on one end and proprietary USB on the other end)
- 5' Audio cable (male 3.5mm miniplug on one end and male 2.5mm sub-miniplug on the other end)
- Zippered storage pouch
- Instruction Manual on CD-ROM
- Quick Guide
- Safety Guide
- Compliance statement
- "Replacement of the Mains Unit" sheet
- portable, folding, on-the-ear design
- padded, closed earcups and adjustable headband
- Bluetooth® wireless operation with advanced aptX audio circuitry for streaming high-quality stereo sound from aptX-enabled devices
- built-in microphone and wireless earcup controls for hands-free conversations using compatible Bluetooth cell phones
- integrated controls on the right earcup for track, volume, and answer/end call functions
- rechargeable lithium-polymer battery included
- single battery charge gives you:
- up to 20 hours Bluetooth talk time
- up to 10 hours Bluetooth listening time
- advanced Duofol drivers for outstanding sound quality
- frequency response 15-22,000 Hz
- 60" detachable audio cable with stereo mini plug included for wired listening options
- airline adapter, USB charging cable, multi-country wall charging adapter, and carrying case included
- weight: 3.7 oz.
- warranty: 2 years
- Our 60-day money-back guarantee
Sennheiser MM 400-X Reviews
Average Customer Review(s):
Thanks for submitting your review
Features and Specs
|Earcup Width x Height||2.275" x 2.255"|
|Mic For Taking Calls||Yes|
|Frequency Response||15-22k Hz|
|1/4-inch Adapter Included||No|
|Parts Warranty||2 Years|
|Labor Warranty||2 Years|
Overview: The Sennheiser MM 400-X headphones are an accessory that allows you to enjoy your digital music files on your mobile phone or portable music device, including those equipped with Bluetooth technology. The MM 400-X can be used wirelessly, or in places where Bluetooth isn't available, you can plug them in and use them as wired headphones.
Bluetooth Wireless Reception/Transmission: The MM 400-X features Bluetooth v2.1 wireless reception and transmission with a built-in microphone for cable-free use with select Bluetooth enabled phones and audio devices. Supported Bluetooth profiles include A2DP (Advanced Audio Distribution Profile), AVRCP (Audio/Video Remote Control Profile), HSP (HeadSet Profile), and HFP (Hands-Free Profile). The MM 400-X saves the connection profiles of the last eight devices with which it was paired; when turned on it automatically tries to connect with one of those devices.
Note: Not all Bluetooth enabled audio devices will be compatible.
apt-X: The MM 400-X headphones are equipped with apt-X, an audio coding technology that works within Bluetooth to wirelessly deliver CD-quality audio from your portable music device to the headphones. With apt-X, you can listen to your digital music files in crisp, pure, and full stereo sound.
Controls: On the right ear-cup there are integrated controls for your connected phone or audio device. Audio controls include volume, skip forward or backward, fast forward or rewind within a song, play, and stop. Phone controls include volume, accept call, reject call, end call, redial, voice dial, and mute.
Note: All control functions must also be supported by the connected device.
Battery Pack: The MM 400-X has a removable BA 370 PX Lithium-Polymer battery pack (3.7 volts DC/1 Wh) which provides up to 10 hours playback using Bluetooth reception. A power supply with US, UK, European, and Australian plug adapters is included to charge the battery pack; charging time is approximately three hours. The headphones can also be charged using a computer's USB port.
Collapsible Design: These headphones feature a collapsible design with metal-reinforced headband to ensure portability and durability.
Cord & Adapter: The MM 400-X will also work as wired headphones, useful when Bluetooth connection is not an option. The headphones come with a 60" mini-jack cable terminated by a 3.5mm connector for a wired connection. An in-flight audio adapter (dual mono 3.5mm) is included for added convenience.
Carrying Case: A nylon carrying case is included to protect the headphones during storage or transport.
Specifications: The MM 400-X has the following specs:
- Frequency Response: 15-22kHz
- Nominal Impedance: 590 Ω active mode; 100 Ω passive
- SPL (1 kHz/1 Volt): 107 dB
- THD (1 kHz): < 0.1%
- Connectors: 3.5mm, 3.5mm double mono plug in-flight adapter
- Weight: 3.7 ounces (105 grams)
- Version: 2.1 + EDR
- Range: up to 33' (10 meters)
- Transmission Frequency: 2.4 GHz
- Transmission Power: 8 dBm
- Profiles: HSP, HFP, A2DP, AVRCP
- Codec: SBC, apt-X
Our Product Research Team
At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.
2 questions already asked
Hi Tim C, Please check on this but as far as I know the iPhone does not support AptX. The Mac OS does and I believe Windows does too, but I believe the iPhone does not. One thing you might want to know about these headphones is that they have a crystal clear high and mid range but very poor low range. I ended up returning them and trading them for the Dr Dre BT headphones, which are more expensive and don't have as clear of a high range but they have a significantly much better bass response. [ Alex Apr 08, 2014 ]
They were a gift and my daughter says they work great [ Fred Apr 08, 2014 ]
You should be good to go!! As long as you have Bluetooth [ Fred Apr 08, 2014 ]
The MM 400-X can be used wirelessly, or in places where Bluetooth isn't available, you can plug them in and use them as wired headphones. [ Jeff Dec 13, 2013 ] Staff