The Hifiman EF400 and the Hymalaya Pro Gold modules were kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.
The Hifiman EF400 upgrade program will set you back $149 for the Hymalaya Pro Silver modules and $299 for the Pro Gold. The program is only available for EU customers and you must own an EF400 unit that has to be sent to the Hifiman service center in order to receive the upgrade. Please visit Hifiman’s official store for more information.
The Hifiman EF400
The Hifiman EF400 is an all-in-one DAC and headphone amplifier that uses Hifiman’s own designed Hymalaya R2R DAC module to do the digital to analog conversion. The circuit is based on a four-channel differential design with a buffer, an active filter and a high current Class AB amplifier with a maximum power output of 4.4W per channel at 36Ω loads.
The device has a single USB digital input (with type-C and type-B plugs), balanced XLR and single ended RCA line outputs plus four headphone outputs (4-pin XLR, 4.4mm, 6.35mm and 3.5mm). You can also select high or low gain and NOS or OS filters.
You can read the full Hifiman EF400 review here.
Hifiman Hymalaya upgrade program
The EF400 is equipped with a 1st generation Hymalaya R2R DAC module. Meanwhile Hifiman has introduced the 2nd generation modules, known as the Hymalaya Pro, that are available in three different variants and offer better measured performance in comparison to the original.
They are the Pro Gold, the Pro Silver and the LE, from the best to the worst when it comes to measured THD and dynamic range. The LE modules are used in Hifiman’s EF500 DAC/amp, the Pro Silver in the EF600 and the Serenade models while the Pro Gold is saved for their flagship unit, the EF1000.
Hifiman is currently running an upgrade program where your EF400 or Serenade models can be upgraded with the 2nd generation Hymalaya modules. The Serenade can be upgraded with the Pro Gold modules and the EF400 with either the Pro Silver or the Pro Gold.
You can read more details about Hifiman’s Hymalaya upgrade program and my review of the Pro Gold modules here.
DIY installation of the Hymalaya modules
The DIY installation of the Hymalaya modules is not officially supported by Hifiman. However, if you are skilled enough you can try to do it by yourself but you are going to void any warranty left. If you don’t care or your warranty has expired, then drop Hifiman an email asking if they can send you the modules to install them by yourself as it is pretty easy and doesn’t require any special electronics knowledge.
Upgrading the Hifiman EF400
Opening the chassis of the EF400 is as simple as removing a few screws. Then, you can pull out the lid to uncover the internals of the device. Inside you can spot the separate DAC board where the original Hymalaya R2R DAC module is socketed and secured with two small screws.
The board already includes reception holes tailored for the Pro modules where you can solder them after you remove the old one. Since I am not very skilled with soldering iron, Hifiman was kind enough to send me a new board that had soldered sockets ready to receive the modules.
The only thing I had to do now was to remove the old board from the chassis and install the new one where it was very easy to plug the Pro Gold modules in their sockets. The procedure is simple and doesn’t require soldering or any special tools other than a screwdriver. The only thing that you have to do is to remember that the module with the small green spot is for the right channel and the other one with the white is for the left. Now, the EF400 was upgraded to the EF400 Gold and was ready for music listening.
Listening impressions
For readers that don’t own the Hifiman EF400 and are too lazy to read the review let us summarize that the main sonic characteristic of the EF400 is its analog-like and organic timbre. The EF400 is musical, melodic and engaging but at the same time technical and transparent enough as a modern DAC should be.
However, when compared with better R2R DACs, like say the Hifiman Serenade, or other competitive D/S DACs, it is somewhat lacking in overall clarity and transparency. Some users might also find the EF400 as too warm sounding, not as energetic and brilliant as they would have liked and maybe a little rolled on the treble.
Swapping the stock module with the Pro Gold ones, instantly fixes all these issues, effectively transforming the Hifiman EF400 Gold into a technically advanced device, closing the above mentioned gap. The best part is that all these technical advancements happen without affecting its well valued timbral and tonal qualities.
The Hifiman EF400 Gold still sounds natural and organic with minimal digital glare but it has gained leaps in clarity and transparency. If you have read the Hymalaya upgrade review then you will remember a remark saying that swapping the Pro Silver for the Pro Gold modules in the Serenade model yielded a lot of meaningful but not that pronounced sonic differences.
The same observations are radically different in the case of the Hifiman EF400 where the module exchange yields immediately more noticeable sonic improvements. The differences in the technical performance and the overall fidelity between the Hifiman EF400 Gold and the stock EF400 are so audible that it is like buying a higher tier device.
More listening impressions
Doing an A/B listening comparison between the Hifiman EF400 Gold and the EF400 was not too difficult because it was possible to swap the two boards by just unplugging a few cables. Thus i hadn’t to rely too much on my memory and was rather easy to discern the sonic differences between the two devices. The EF400 Gold is cleaner sounding and more transparent by a fair margin. The music background is blacker and the textures are more refined and less grainy, especially in the higher registers. The treble is also more extended and energetic, the sound gains depth and micro-detail quantity without becoming analytical or clinical.
An especially notable improvement has to do with the bass region which sounds more textured and layered with better definition in comparison to the stock EF400. Actually, definition and articulation are improved throughout the whole frequency range and not the bass alone. The Pro Gold modules open up the soundstage a little bit and help a lot with the imaging accuracy and the separation of the various sound elements within the stage.
As said earlier in the beginning, the most important thing is that everything happens while the Hifiman EF400 Gold retains the original analog-like and organic timbre. The sound is still exceptionally musical and expressive as we know it, with plenty of colorful harmonies and a deep engagement factor with all kinds of music. Listening to the Hifiman EF400 Gold is like a veil has been lifted from the sound but without negatively affecting its timbre quality to become sterile or artificial, not even remotely.
Is the upgrade for everyone?
There is a chance that some people might not like what the EF400 Gold upgrade brings to the table and prefer the original sound signature, as it usually happens in audio where there is a great deal of subjectivity and taste involved.
The Hifiman EF400 Gold doesn’t sound as warm or smooth in the treble as the EF400, it is more energetic and less relaxed. Its textures are a bit leaner and drier than the stock model which sounds thicker and more lush in comparison. The bass of the original EF400 has more weight and fullness while the soundstage appears a bit more holographic, albeit less precise. The treble of the EF400 is softer and less brilliant but also more grainy and less refined while the mids are more colourful but less clean and not as resolving.
Comparing the two versions side by side, you can say that the EF400 is the most retro sounding of the two, somewhat reminiscent of old school tube sound, while the EF400 Gold has a more modernized and technically advanced presentation without sacrificing timbre.
In the end
Upgrading the Hifiman EF400 with the Hymalaya Pro Gold (or even the Silver) modules is a cost effective way to improve its technical performance without loosing its well valued analog-like and organic sonic characteristics.
For a small amount of money, the EF400 gains meaningful technical advancements and becomes the only affordable R2R DAC in the market that can compete head to head with much pricier offerings by Hifiman or other brands, giving its owner a good taste of high-end R2R sound at a fraction of the cost.
Copyright – Petros Laskis 2025.
+ Improved technical performance and transparency
+ Better clarity and definition
+ Enhanced resolution and refinement
+ Advanced imaging precision and separation
+ More energetic and extended treble
+ Better low-end layering and articulation
+ Doesn't make the sound clinical or sterile
+ Possible DIY installation
+ Not too expensive
+ A cost effective way to upgrade the EF400
- Only available for EU customers
- DIY installation is not officially supported
- Slightly less warm and smooth than stock EF400
- Somewhat leaner and drier textures than stock EF400
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