HiFiMan EF600 Review: a powerful and high-performing DAC/amp

The HiFiMan EF600 is a balanced R2R DAC with a headphone amplifier and integrated Bluetooth receiver, featuring an original vertical design and powerful enough to optimally drive virtually any headphone.

Overview

HiFiMan Electronics is a Chinese company founded in 2007 by Dr. Fang Bian. HiFiMan gained widespread popularity with its line of advanced planar magnetic headphones, which have won numerous awards in recent years and are considered among the best in their respective price ranges. In addition to headphones, HiFiMan produces other high-end audio electronics: DACs, headphone amplifiers, and portable music players. However, for many years, its lineup of reasonably priced desktop headphone amplifiers was limited to the EF6 model, specifically designed for the HE-6 headphones and priced at around $1600—not exactly cheap.

Things changed completely at the end of 2022, when HiFiMan released the EF400, a powerful and high-performing headphone amplifier with an integrated R2R DAC priced at around €600, and currently available for just over €500. The EF400 was highly successful, leading HiFiMan to expand its amplifier range by introducing a larger sibling, the EF600, more flexible and more powerful, and more recently the EF500 and EF499 models, which are more affordable and equipped with network connectivity.

Like its smaller sibling EF400 and many other HiFiMan DACs, the EF600 performs digital-to-analog conversion using a DAC based on R2R technology. This technology uses a carefully designed resistor ladder network, typically controlled by FPGA units, to convert digital signals into analog. According to enthusiasts, when properly implemented, this solution delivers a richer, more natural, and spatially defined sound compared to converters using other technologies. However, the need for highly precise electronic components often makes DACs of this type quite expensive. The EF600 uses a high-performance R2R DAC called Himalaya Pro, which improves upon the already excellent Himalaya found in the EF400, offering lower distortion, a wider dynamic range, and a more refined sound.

The amplification section relies almost entirely on discrete components (transistors, diodes, resistors, capacitors) and delivers an impressive 5.12 W at 32 ohms via the balanced output (1.8 W via the unbalanced output). It is very rare to find a high-quality R2R DAC and such a powerful headphone amplifier combined in a product under €1000, and the EF600 currently costs only €719. The price has dropped significantly in recent weeks.

Features and functions

The EF600 comes in a large, no-frills cardboard box containing only the amplifier and a standard power cable. It stands out for its solid, professional appearance and its distinctive vertical design. This shape allows for better heat dissipation through natural convection (air enters through vents at the bottom, is heated by the large toroidal transformer, and exits through the top vents). It also reduces horizontal desk space usage and allows the EF600 to be used as a headphone stand. Leaving your headphones on the EF600 looks great and helps keep your desk tidy; however, over time the unit tends to heat up—especially at the top—so headphones placed on it will also warm up, which some users may find unpleasant.

The “tower” layout, despite its advantages, proved problematic in our workspace: it is impossible to place the EF600 in the classic position behind the monitor, as the volume knob and buttons are hidden by the screen. Placing it in front of the monitor blocks the view entirely. The only option is to move it to the side, and with large monitors or multi-display setups, the EF600 may end up quite far away. This also increases the likelihood of needing longer cables.

On the rear panel, we find the power socket and power switch, two balanced XLR inputs and two outputs, as well as two unbalanced RCA inputs and outputs. This allows the DAC section to be used independently (connecting an external amplifier) or an external DAC to be connected to the headphone amplifier. The placement of the power switch on the rear, like the EF400, is clearly inconvenient. Available inputs include USB-B and USB-C, which cannot be used simultaneously and are not selectable via a switch.

There is also a coaxial digital input, which can be used to connect devices such as a CD player or a TV—a welcome addition compared to the EF400. The front panel is simple and well designed, with symmetrically arranged buttons. The volume control is lever-type and not particularly precise. On the top of the unit, two buttons are present: the first changes gain and the digital conversion mode between High Gain NOS / High Gain OS / Low Gain NOS / Low Gain OS. NOS stands for “No OverSampling”: in this mode, the signal is converted more directly, without altering its frequency and with less use of complex audio filters.

Whether oversampling is preferable in A/D conversion is a complex and long-debated topic in high-fidelity audio. In the case of the EF600, the same considerations apply as for the EF400: NOS mode appears more defined and less “veiled,” while OS mode is characterized by greater warmth in the low frequencies. The choice between the two will likely depend on the headphones used and personal preferences.

The second button on the right selects the input among the four available: USB, Bluetooth, RCA, XLR. The addition of Bluetooth wireless connectivity is another welcome feature compared to the EF400, although most buyers will likely prefer the higher performance of wired connections. Signal reception is excellent, with strong range and resilience to obstacles. At the bottom are the headphone outputs: XLR and 6.35mm.

The EF600 is designed in a fully balanced architecture: two Himalaya Pro R2R modules handle digital-to-analog conversion for the left and right channels. The powerful amplification stage is also fully balanced, delivering up to 5.12W at 32 ohms. Everything is powered by a large, heavy toroidal transformer with OFC copper windings. Decoding supports up to 24-bit / 768kHz PCM resolution. Note, however, that DSD and MQA are not supported.

Listening test

We had the opportunity to test the EF600 with a wide variety of headphones, including some of HiFiMan’s most famous planar magnetic models: Sundara, Edition XS, Arya Stealth, and HE6v2 SE. To evaluate its performance with high-sensitivity, low-impedance headphones, we also tested it with Grado SR80E and closed-back HiFiMan HE-R9. The claimed power is confirmed in listening tests: the EF600 has power to spare.

The EF600 requires many hours of burn-in: initially it sounds thin and somewhat “boxed-in,” but over time its true character emerges—warm, dynamic, and musical. The EF600 is clearly designed as an ideal companion for HiFiMan headphones, and indeed it brings out the best in them: it sounds dynamic, musical, and never fatiguing. Overall, the sound is full and rich, while maintaining good instrument separation within a fairly wide and realistic soundstage, with excellent handling of sound effects moving across channels.

With the Arya in particular, the pairing is, in our opinion, excellent: the headphone’s precision and detail combined with the EF600’s warmth and musicality make for a great match. The EF600 was also able to drive the HE6v2 SE—notoriously demanding and inefficient headphones—effortlessly and with excellent results. We cannot think of another DAC/headphone amplifier combo under €1000 capable of driving them so well.

The EF600 also performed very well with Grado and HE-R9 headphones, delivering a particularly warm and dynamic sound. However, with these highly efficient headphones, the usable volume range is very limited: even in Low Gain mode, beyond 9 or 10 o’clock the sound pressure becomes excessive.

Conclusions

In summary, the EF600 is a DAC/headphone amplifier combo that impressed us with its power, dynamics, and ability to drive even very demanding headphones. Due to its characteristics, it is particularly suitable for medium/low-sensitivity headphones such as HiFiMan planar magnetics, as well as high-impedance headphones. Considering its more refined sound and greater flexibility, the current price difference compared to the EF400 (about €200 more) is fully justified, and we can confidently recommend it to all headphone enthusiasts who need a particularly powerful and high-performing DAC/amplifier combo.

Until recently, the EF600 cost around €1050 in Italy—a significant amount—but with the price drop to just over €700, its value for money has improved dramatically, making it a very strong choice in its category, especially for those planning to drive HiFiMan headphones or other power-hungry models. The excellent range and reception of the Bluetooth signal are an added bonus.