Wired Over-Ear Planar Magnetic Headphones and Hybrid Vacuum Tube/USB DAC Headphone Amplifier

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HiFiMAN Truly Delivers: HIFIMAN HE400i Planar Magnetic Headphones


HiFiMAN doesn't build your average pair of headphones; they build works of art to truly introduce you to your music. The HiFiMan HE-400i planar magnetic headphones let you hear every minute detail in your music like you've never heard before. The HE-400i feature some of the finest headphone engineering and craftsmanship available today to bring you a pair of headphones that, once you put them on, you won't want to take off.


An added benefit of the HE-400i headphones is that, due to their highly efficient operation they can be plugged directly into your smartphone, tablet or any other output device; it is important to note that to take full advantage of the HiFiMAN HE-400i a headphone amplifier is highly recommended. Don't let your ears toil away with a mediocre pair of headphones when you could be basking in the glow of the HE-400i headphones from HiFiMAN!

Lose Yourself in Your Music

HiFiMAN engineered the HE-400i headphones with full size planar magnetic drivers which produce warm, balanced sound. The advantage planar magnetic drivers offer over your average headphone drivers is that they cover a larger surface area to deliver outstanding sound detail and spaciousness. Their incredibly natural timbre combined with the open back design make these headphones sound like you're sitting in the crowd at a show.

Listen in Luxury

With the HE-400i headphones, listener fatigue won't be a problem. These sleek over-ear headphones offer FocusPad ear pads, beveled ear pads made from a mix of pleather and velour to improve both comfort and durabililty. The newly designed headband provides a greatly improved pressure pattern. They are also 30% lighter than comparable headphones. The HE400i headphones offer you best-in-class comfort.

Quality Connection

The quality of your headphones doesn't matter if you don't have a connection to match. HiFiMAN designed screw terminal inputs into each ear cup for a secure connection. Each connection uses a separate ground lead for each channel to significantly reduce unwanted crosstalk between channels, improving your overall sound quality to optimize your listening experience.

HIFIMAN EF-100 Hybrid Vacuum Tube/USB DAC Headphone Amplifier

The HIFIMAN EF-100 Headphone Amplifier Offers an Incredible Listening Experience

The HIFIMAN EF-100 is a powerful hybrid headphone amplifier and integrated amplifier. Housed in its compact chassis lie three independent amplifier sections: a vacuum tube input stage works as a shared preamp, a Class AB headphone amplifier, and a Class T speaker power amplifier. Benefiting from vacuum tube technology, both headphone amplifier and power amplifier sound warm, smooth, detailed and musical. Working as a hybrid headphone amplifier, EF-100 can produce a 2w output under a 32 ohm load so it can easily drive many high performance headphones. In addition, EF-100 can also serve as a hybrid power amplifier to drive speakers of moderate to high efficiency. In power amplifier mode, the amplifier output line is fully independent from the digital amplifier line used in the headphone amplifier. Driven by front stage’s vacuum tubes, EF-100 combines the warmth vacuum tubes are known for with the high efficiency of a digital amplifier. It is the best of both worlds. When EF-100 is used as a power amplifier, it can give 4.5 watts per channel so it can drive HIFI speakers of moderate to high efficiency. At last, with its versatile design EF-100 can bring music to life from a variety of sources for both headphones and speaker applications.

The HIFIMAN EF-100 Headphone Amplifier Offers an Incredible Listening Experience


Wired Over-Ear Planar Magnetic Headphones
Quantity: 1

General Features:

  • Orders limited to one unit per customer through 1/3/2016
  • Wired Planar Magnetic Over-Ear Headphones
  • Planar magnetic drivers offer a detailed, warm listening experience with minimal distortion
    • Not sure what Planar Magnetic Drivers are? Click here to read our Headphone Driver Type knowledge base article
  • Open back design provides an incredibly spacious sound stage
  • FocusPad hybrid earpads
    • Beveled pleather and velour cushions for vastly improved comfort and sound quality
  • 30% lighter than comparable headphones for maximum comfort
  • Newly designed headband with an improved pressure pattern for improved comfort
  • Primary Color: Smoky Gray
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Product Specifications:

  • Frequency Response: 20-35,000 Hz
  • Sensitivity: 93dB
  • Nominal Impedance: 35 Ohms
  • Cable:
    • Detachable: Yes
    • Cord Length: 5 ft. (1.5m)
  • Plug Size: 3.5mm
  • 1/4" adapter included

What's in the Box?

  • HiFiMAN HE-400i Planar Magnetic Headphones
  • 5 ft. Audio Cable w/ Screw-On Terminals
  • 3.5mm to 1/4" Adapter
  • User Guide
  • HiFiMAN Social Media Card
  • Serial Number Card

Note: HiFiMAN products can only be shipped to customers in the United States

Also found as: HE400i


Hybrid Vacuum Tube/USB DAC Headphone Amplifier for High Performance Headphones
Quantity: 1

General Features:

  • Premium audiophile hybrid vacuum tube headphone amplifier
  • Features 3 independent amplifier sections:
    • Vacuum tube input stage that functions as a preamp
    • Class AB headphone amplifier
    • Class T speaker power amplifier
  • Listen through your favorite headphones or a pair of speakers
  • Integrated 3.5mm, stereo RCA and type B USB inputs
    • USB input and built-in DAC allow you to stream CD quality music from your computer
  • Full size front stereo headphone output
  • Binding post speaker connectors
  • Vacuum tube input stage brings warmth, detail and spaciousness to your music
    • Utilizes a single 6N3J dual triode vacuum tube input stage
  • High output headphone amplifier designed for use with high performance headphones like the HiFiMAN HE-560 and HiFiMAN HE-6
    • Class AB solid state design
    • Output Impedance: 32-300 ohms
      • Output at 32 ohms: 7.8V, 2W
    • Signal-to-Noise Ratio: 95dB
    • Frequency Response: 20-20,000 Hz
  • Drives speakers with moderate to high efficiency levels
    • Class T solid state design
    • Power Output: 4.5W x 2 into 4 ohms
    • Frequency Response: 20-20,000 Hz
  • Dimensions: 7-7/8"W x 10-3/4"D x 3-3/4"H
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Note: HiFiMAN products can only be shipped to customers in the United States

Also found as: EF100

Headphone Design

Headphone Type

This is the design of the earpieces on the headphones. Some headphones go inside the ear, while others rest on the outside of the ear. This helps you know exactly what type of headphones you will be receiving.

In-Ear: The ear buds go into the ear. Most often, the right and left ear buds are two separate pieces.

Enclosed-Ear: Usually are found on the larger headphones. They rest on top of the ear and have padding for comfort, as well as enclosing the ear to the speaker. This type of headphone helps to filter out surrounding noise.

On-Ear: This type of headphone involves the speaker sitting gently on the ear without going in the ear or sealing it off.

Headband Type

Headphone type refers to the construction of the headphones.

Around the Ear means that the headphones wrap around the ear to provide a secure fit. This is most often seen in active and sports headphones.

Around the Neck means that the headphones wrap around the neck. This is also seen in active and sports headphones.

Earbuds means that the right and left sides of the headphones are separated and will fit securely into the ear. These are small, compact, and user friendly.

Over the Head headphones mean that the right and left speakers are connected with a support that goes over the head and rests on top. This is the typical headphone type.

Over the Head
Specifically For
Some headphones can use an IR Transmitter in your vehicle, while some can be plugged into your media device and be used on the go or at home.
Headphone Application

This is the application that the headphones are designed for. Each application has unique features that make it perfect for particular uses.

DJ: These headphones are durable, loud, and will often allow for one ear listening.

Gaming Delivers explosive sound and allows you to communicate with others.

Home Hi-Fi: These audiophile headphones are engineered to produce high fidelity and accurate audio.

Home/Office: These headphones are designed to produce rich, brilliant sounds that the artists would appreciate.

Sports: Designed for active use. These headphones are made to stay in (or on) the ear during workouts.

Kids: Feature noise limiting technology so that your little ones don't damage their ears listening to music too loud.

On-the-Go: On-the-go headphones are lightweight and often fold up for easy storage and portability.

Student: Compact and rugged enough to survive life in a backpack; inexpensive enough to not hurt the wallet of a student.

Studio: Reproduce music perfectly without any coloration. Look here for reference quality studio monitoring headphones.

Traveler/Airplane: These headphones are compact, lightweight, and have a portable design.

Home Hi-Fi
Acoustic Principle

The basic design of the headphones. There are 3 different types:

Open: Have ports that allow air through the back of the diaphragms, enabling the headphones to sound like the music is coming from an outside source.

Closed: Completely sealed and have no air passing through the diaphragms. Sounds like you are in a closed off room.

Semi-open: Have slots or ports in the back of the cup and are partially open. This allows for a mixed sound between an open and closed headphone.


General Features

Noise Reduction technology removes unwanted noise from a signal. Background or ambient noise can be removed to produce clearer speech and enhanced hearing. Typically these Active Noise Canceling (ANC) headphones are powered and use batteries to activate the noise canceling technology. Also referred to as Noise Reduction or Noise Cancellation.
Built-In Microphone
This means that the headphones or earbuds have a built-in microphone. This can be a microphone on the cord, built into the headphone, or even a boom microphone. These mics can be used for music devices like iPods, for Smartphones to make and receive calls, or for gaming purposes.
Headphone Connection
This is how the headphones connect to the audio source.

Corded means that the headphones use a cord to transfer the audio signal.

Bluetooth means that the audio signal is transmitted from your device to the headphones via a Bluetooth connection.

Corded or Bluetooth means that the headphones can be used as corded headphones or as Bluetooth headphones. They have an input in one or both earcups for use as a corded headphone while they also have a built-in battery for use as Bluetooth wireless headphones.

Wireless means that the audio signal is transmitted wirelessly to the headphones.

Volume Adjustment
Volume Adjustment means that the headphone (independent of the source) can adjust the playback volume. Many headphones and ear buds have in-line volume control, which allows adjusting the audible volume from a switch on the headphones cord. Other headphones have a volume knob on the headphone can.
Connector Type
The type of connection the headphones use to connect to receive the audio signal from a music source. Traditional headphones use an analog 3.5mm headphone jack. Newer technology has allowed digital signals to be sent directly to the headphone using an Apple Lightning or USB-C cable.
Jack Size
Refers to whether the headphones use a 3.5mm or 1/4" headphone jack connection.
Jack Angle

The Jack Angle refers to the angle of the input jack on the headphone cable.

Straight Jack: Straight plug with no angle.

Angled Jack: Angled plug, usually a 90 degree angle.

Swivel Jack: A swivel jack is able to swivel between a straight plug and an angled plug.

Straight Jack
Included Adapters
Refers to the connection adapters included with the headphones like 3.5mm or 1/4" input adapter as well as airplane adapters that let you use your headphones with airplane specific headphone jacks.
1/4" Adapter
Detachable Cable
Refers to whether the cable can detach from the headphones. If a pair of headphones has a detachable cable, the cable can be replaced with a longer cable, one with (or without) a microphone or if you accidentally damage the cable.
Color Shades
Primary color shades of the headphones.
Refers to materials used to build the headphones. Most headphones are built from some combination of plastic and metal to give you a durable pair of headphones.
Ear Cushion/Earbud Material
Refers to the material that the ear cushions/earbuds are made from. Ear cushions and earbuds are available in a variety of materials, ranging from basic rubber eartips to plush leather ear cushions intended for maximum comfort.
Protein Leather
Water Resistant
This refers to the level of water resistance of the fitness tracker. Some fitness trackers are water resistant and can be used while swimming, while others are only splash proof or should not be used near the water.
Refers to whether a pair of headphones can be folded up. These headphones feature hinges in the frame above the earcups that allow the headphones to neatly fold into a much more manageable size. Folding headphones are perfect for anyone who spends a lot of time traveling and needs a compact pair of headphones that can fit in their bags.

Audio Features

Driver Type

The physical design of the driver in the headphones.

Balanced Armature:
A balanced armature driver uses a coil wrapped around an armature which is held in between two magnets until it is stimulated by an electrical current. When stimulated, this armature is magnetized which causes it to rotate one way or the other around a pivot point which moves the diaphragm to create sound. Balanced armature driver headphones are generally earbuds and can have multiple drivers in each earbud.

Dynamic drivers are the most common driver type. They feature a permanent magnet, usually neodymium, a voice coil and a conical diaphragm to drive your music. A dynamic headphone driver looks pretty much identical to any typical home theater speaker.

Electrostatic drivers are made up of an extremely thin membrane, usually a coated PET film, stretched between two metal plates. An electrical signal is applied to the metal plates to create an electrical field which, depending on its polarity, draws the speaker diaphragm toward one of the plates which forces air through the perforations in the diaphragm which generates the sound wave.

Planar Magnetic:
A planar magnetic driver is made up of a large membrane suspended between two sets of oppositely aligned magnets. An electric charge is applied to the membrane to induce movement and produce sound waves.

Planar Magnetic
The opposition to electric current, a higher impedance means a higher electrical resistance. This is measured in ohms.
35 ohms
An efficiency or sensitivity rating tells you how effectively a speaker converts power into sound. The higher the number, the more efficient the speaker and the louder it will play with the same input power. An efficient speaker helps you maximize your available power. Most sensitivity ratings measure the speaker's output with 1 watt of input, 1 meter from the speaker. Some speakers' sensitivity is measured with 2.83 volts of input, instead of 1 watt.
Efficiency (1w/1m) is not an accurate indicator of a subwoofer's output capability and should not be used as a comparison to other speakers or subwoofers to determine which one is "louder".
93 dB
Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
20 - 35000 Hz
Audiophile headphones represent some of the finest headphones available. Audiophile headphones produce genuinely outstanding sound quality as well as extraordinary build quality, components and comfort. They are truly the finest headphones available.
Built-in Amplifier
This refers to whether the headphones have an amplifier built-in.

What is in the Box?

Main Product
The main product in the box.
HIFIMAN HE-400i Headphones
Accessories included with the headphones
1/4" Adapter
Paperwork included with the product.
User manual
Warranty/Registration card
Serial number card

Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Summary of Customer Ratings & Reviews

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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: HIFIMAN HE-400i + HIFIMAN EF-100

  • Differences Between Headphone Acoustic Principles | Open, Closed, & Semi-Open
  • Headphones Based on Musical Preference | What Type of Listener Are You?

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Wired Over-Ear Planar Magnetic Headphones and Hybrid Vacuum Tube/USB DAC Headphone Amplifier


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