HIFIMAN EF400 all-in-one decoding headphone amplifier reviewWhat I want to share with you today is a combination that I have used a lot recently. The amp part is the HIFIMAN EF400 all-in-one decoding amp. As a member of HIFIMAN self-developed HYMALAYA DAC chip product line, HIFIMAN EF400 not only has high quality, but also has a relatively high cost performance.

HIFIMAN EF400 specs and features:

  • 125±3dB channel separation
  • 118±3dB signal-to-noise ratio
  • 6.35mm/3.5mm/4.4mm headphone port
  • Low/High Gain NOS, Low/High Gain OS
  • $582 – Check latest price on AliExpress, Amazon US, Amazon Germany or other Amazon countries

01/ Appearance Design and Control

The first impression of seeing the HIFIMAN EF400, in addition to the minimalist yet delicate design, the overall layout, functions and ports also fully consider the needs of users. Silver black and brushed aluminum alloy panels also greatly enhance the sense of grade of HIFIMAN EF400.

The logo in the upper left corner of the panel represents the identity of the HIFIMAN EF400 using the self-developed “HYMALAYA” DAC chip. As the forerunner of China’s self-developed DAC chip, HIFIMAN’s self-developed HYMALAYA DAC chip basically represents one of the highest standards of decoding chips at present.

In terms of control, HIFIMAN EF400 provides two independent function keys. The function key on the left is the gain knob. HIFIMAN EF400 provides two high gains (High Gain NOS, High Gain OS) and two low gains (Low Gain OS, Low Gain NOS). The function key on the right is the volume key, and the damping of the two knobs is very good.

In addition to excellent workmanship, rich input and output ports are also one of the features of the EF400. The front of HIFIMAN EF400 provides four commonly used audio output ports, namely 6.35mm, 3.5mm, 4.4mm headphone port and 4-core headphone balanced output port.

On the back of HIFIMAN EF400, it integrates BAL OUT (XLR balanced output right/left channel), RCA OUT (RCA single-ended output port, USB Type-C input, USB-B input and AC power input port/power supply switch). HIFIMAN EF400 basically includes various mainstream ports at present, and can fully meet the output requirements of the headphone.

Probably because of the global version, there is also a 115V/230V AC switch at the bottom of the HIFIMAN EF400 to adapt to the input voltage requirements of different regions.

Probably because of the positioning, there are no optical fiber and coaxial ports on the HIFIMAN EF400. From this point of view, the product positioning of HIFIMAN EF400 is still very clear. This is an all-in-one decoding amp for the public, which can match the HIFIMAN EF400 well without a professional front-end. It can be common devices such as mobile phones and computers, or products such as players that support Type-C port. For ordinary music lovers, the front-end investment can be greatly reduced.

02/ Performance and Hardware

When it comes to professional decoding amps, it actually needs a large current to drive, which requires a built-in transformer. Inside the HIFIMAN EF400 is an oxygen-free copper anti-seismic potting toroidal transformer, which is made of pure copper. Here we will talk about the difference between aluminum core and copper core transformers. The copper core has high strength, high stability, corrosion resistance, low resistivity (relatively weak electromagnetic interference), low energy consumption, low voltage loss, and low temperature. Of course, the price will be much more expensive.

In addition, HIFIMAN EF400 is also equipped with a current amplifier circuit of 30000uf capacitor and a self-developed HYMALAYA R2R DAC chip. The parameters reflected on the HIFIMAN EF400 are: signal-to-noise ratio of 118±3db, total harmonic distortion of about 0.003%, channel separation of 125±3db, maximum output power of 4.4W, and maximum support for 24bit/768KHz PCM sampling. The HYMALAYA chip is actually a “discrete R2R module composed of FPGA+0202 resistors in essence. From the above equipment parameters, the performance is still good. Whether it is total harmonic distortion or signal-to-noise ratio, it has already ranked among the forefront of mainstream DAC chips.

  • Total Harmonic Distortion (Output): 0.002%-0.004%
  • Channel separation: 125±3dB
  • Signal-to-noise ratio: 118±3dB
  • Maximum output power: 4.4W
  • Dimensions: 246.5x228x61mm
  • Weight: about 3.08kg

03/ Sound Quality of HIFIMAN EF400

In terms of equipment matching, the front end is a laptop with Win11 system, which is connected to the amp through a Type-C data cable. With the Foobar2000 player, it should be a choice that does not increase the cost at all. The amp is the HIFIMAN EF400 shared this time. In the selection of the headset, in order to have a more intuitive comparison, the HIFIMAN DEVA planar-diaphragm headphones are selected.

In terms of the texture of the whole sound, because of the addition of HIFIMAN EF400, the layering of HIFIMAN DVEA has become clearer, bringing a more balanced and relaxed listening environment. The low-frequency layering and extension have also been improved to a certain extent, and the resolution has been greatly improved compared to the Bluetooth module or direct computer drive.

Listening to “So Goood” in “Brian Culbertson Live From The Inside” once again confirmed the power of the HIFIMAN EF400. As a smooth jazz with piano as the main melody. In terms of sound, this combination has a good performance whether it is fast-paced transients or silky soft parts. Especially the trombone at the back seems to be able to feel the vibration of the air, and the resolution and separation have become better.

Judging from the experience during this period, in addition to bringing greater thrust, the HIFIMAN EF400 has particularly improved the separation and resolution of the mid-high frequency. With the natural advantages of the open structure of HIFIMAN DEVA, whether it is vocals or musical instruments, the overall sense of hearing becomes more natural and transparent, and the sense of atmosphere becomes more relaxed.

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