HiFiMan EF400

Review: HiFiMan EF400 – Odd One Out

Review: HiFiMan EF400 – Odd One Out

The HiFiMan EF400 boasts a unique blend of features rarely found together. Its remarkable output power, combined with the inclusion of an R2R DAC, sets it apart from the crowd. Moreover, the availability of multiple sound profiles adds to its appeal, particularly for those who own multiple headphones and enjoy experimenting with different pairings.

However, we believe there is room for refinement. The unit’s unpolished upper-treble and subpar imaging and staging performance prevent it from reaching its full potential. While tonal coloration is enjoyable, having a reference-sounding counterpart would be advantageous. It is priced at $529 via Amazon.

Product Tech Specifications

  • Type: USB DAC + headphone amplifier
  • Chipset: 2x HIMALAYA R2R DAC
  • Frequency range: 20 – 20 000Hz
  • Compatibility: PCM up to 24bit/768kHz
  • Inputs: USB-C / USB-A
  • SN/R: 118 +/-3dB (A-Weighted)
  • THD+N (Line out): Between 0.002% and 0.004%
  • Channel Separation: 125 +/-3dB
  • Maximum Power Output: 4.4w per channel
  • Dimensions: 9.7″ x 9″ x 2.4″ (247mm x 228mm x 61mm)
  • Weight: 6.8 lb (3.08kg)
  • Inputs: USB-B and USB-C
  • Headphone Output
      • 3.5mm Single-ended
      • 6.3mm Single-ended
      • 4.4mm Balanced
      • XLR 4-Pin Balanced
  • Line Out
      • Dual XLR Balanced
      • Dual RCA Single-ended

The Design of HiFiMan EF400

The HiFiman EF400 is a substantial and robust desktop amplifier. While it appears comparatively smaller when contrasted with its predecessor, the EF-6, a commanding Class-A amplifier designed explicitly for headphones, the new DAC/Amp still maintains a considerable size.

HiFiMan EF400

The physical dimensions of the HiFiman EF400 measure 246.5mm in length, 228mm in width, and 61mm in height, constituting a moderately large body with a weight of 3kg. Fortunately, the sturdy chassis provides the convenience of placing additional items on top of the DAC, such as a monitor or laptop.

Crafted entirely from aluminum, the HiFiman EF400 boasts a visually and tactically satisfying design, making it a true desktop device that commands attention as the centerpiece of your setup. The EF400’s notable features include large front panel knobs and various connectivity options: four headphone outputs (two balanced, two single-ended), two line outputs (XLR, RCA), and two USB inputs. Importantly, this device functions as both an amplifier and a high-quality DAC.

The Highlights of EF400

The term “R2R” in the context of the HIFIMAN EF400 does not refer to reel-to-reel audio but rather to a resistor ladder DAC design. This design utilizes a resistor-to-resistor configuration employed in the DAC section of the EF400.

The standout feature of the EF400 is its internally developed Himalaya DAC section, which is integrated into the same chassis as a robust high-current amplifier section. This Himalaya DAC design was honored with Japan’s prestigious 2022 VGP gold technology award.

HiFiMan EF400

The EF400 offers two selectable filtering options for digital files within the Himalaya ladder resistor DAC. One option is oversampling, while the other is non-oversampling (NOS). The front panel of the EF400 provides easy access to these filters, labeled as NOS and OS, along with two gain levels for each filter.

The power amplifier section of the EF400 demonstrates a robust high-current design, featuring six large 30,000µf capacitors and a sizable oxygen-free copper wire wound toroidal transformer. To ensure isolation and prevent interference, the transformer, DAC section, and amplifier section are positioned on separate boards within the metal chassis interior of the cabinet.

Digital Format

The HIFIMAN EF400 Himalaya DAC seems to prioritize PCM formats, excelling in that area. It supports PCM 32-bit rates up to 768kHz but doesn’t seem to accommodate other formats. Unfortunately, no sampling rate indicator LED makes it challenging to determine the exact format used unless indicated by the source.

It’s worth noting that MQA folding capabilities are not expected, and while low-level DSD might be possible, it is not confirmed as a compatible format.

HIFIMAN maintains a certain level of discretion when it comes to EF400 specifications. There seems to be an emphasis on the “listen before judging” approach, encouraging listeners to focus on sound quality rather than getting caught up in numbers and graphs.

Performance of HiFiMan EF400

HIFIMAN doesn’t provide an extensive list of numbers and specifications, preferring to emphasize sound quality over technical details. However, one significant number that stands out is the power output rating, officially stated as 4.4 watts per channel. Unfortunately, it doesn’t specify the impedance or whether this rating applies to the balanced or all the front connections.

HiFiMan EF400

Regarding THD-N levels, HIFIMAN provides numbers (0.002% and 0.004%), but they are only listed for the two rear line outputs. It’s unclear which output the higher number corresponds to, as it wasn’t specified. While it’s a useful specification for accessing the DAC separately, unfortunately, the amp section’s specifications are not provided.

The signal-to-noise ratio is 118dB (±3dB), and the channel separation is 125dB (±3dB). However, whether these measurements are derived from the headphone output jacks or the rear line output connections is not clarified.


HIFIMAN seems to have embraced eco-friendly practices recently, as they have moved away from their previous tradition of packaging their headphones in extravagant jewelry boxes adorned with metal hinges and leather covers. Instead, they now opt for a simple brown box with a laminate across the top.

Inside the box, the EF400 is securely nestled within a custom foam mold, accompanied by a thick 3-prong AC cable. While no literature is included, operating the EF400 is straightforward, and instructions are unnecessary.

It’s worth noting that the box containing the power cord carries important information that deserves attention. One significant detail is that by registering your unit with HIFIMAN, you can extend the existing warranty by an additional 6 months. It’s highly recommended to complete the registration process to ensure your coverage remains valid, as a lot can happen within that extra timeframe.

Drivers Dynamics and Sound Quality

The EF400 delivers dynamics when the recording demands it, showcasing its impressive response time with quick rise and decay. It possesses ample power reserves to handle intense and impactful passages effortlessly.

The EF400 leans slightly towards brightness in terms of tonality, yet it retains a well-defined bottom octave that provides a satisfying punch. Enhancing lower frequencies through equalization, particularly below 60Hz, can enhance the impact of the bass.

The EF400 delivers an exceptional soundstage that rivals top contenders in its price range. When paired with high-quality headphones and a premium source, you’ll experience an expansive and precise soundstage that captures macro and micro details.

The EF400 offers impressive layer separation, with cascades of sound raining down upon the listener and accurate panning shifts. You can discern individual layers at various levels, granted that the headphones used can reproduce these nuances effectively.


The HIFIMAN EF400 provides two options to access the DAC section: the rear RCA outputs or the dual-pin XLR outputs.  You can achieve even better performance from the EF400 by using a higher-tier dedicated amplifier. The DAC alone justifies the asking price, making the amplifier section feel like a bonus addition.

Vocals are presented with airiness and presence; the bass is natural, fast, and possesses a substantial body, while the highs are crisp and clean. Overall, the sound signature is pleasant, natural, and well-defined, with precise placement of elements. It provides a nuanced experience with a detailed and accurate soundstage.

It’s worth noting that the two line-level outputs are fixed and unaffected by the volume control or gain adjustments. However, the two filters noticeably impact both rear output ports.

The Advantages and Disadvantages

HiFiMan EF400


  • Sturdy construction
  • Easy setup without the need for drivers
  • Exceptionally high power output
  • NOS mode delivers smoothness in bass and mids akin to R2R
  • OS mode provides impactful and dynamic punch
  • Single-ended output pairs well with high-impedance headphones
  • Competitive Pricing


  • Lack of support for DSD format
  • Absence of analog or optical input options
  • Not the optimal choice for low-impedance, high-sensitivity loads
  • Subpar imaging and staging capabilities
  • The sound may lack nuance in terms of micro dynamics and bass texture
  • Treble resolution is not the highest in both NOS or OS modes
  • Requires warm-up time to achieve optimal sound quality


The EF400 offers a rare combination of unique features in a single package. The inclusion of a high-output power and R2R DAC is a notable advantage. Additionally, the availability of various sound profiles adds value for those who enjoy experimenting with different headphone pairings.

However, there is room for improvement as the unit falls short regarding upper-treble refinement, imaging, and staging performance. While tonal coloration is pleasing, having a reference-sounding option alongside it would be beneficial.

Furthermore, the absence of DSD support may deter some potential buyers, and the high output power limits its compatibility with sensitive IEMs, reducing flexibility in pairing options.

The EF400 can be an enjoyable addition to an existing source collection, but it may not suffice as the sole source for all your needs.

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