In this feature, we review the HIFIMAN EF600 which is a desktop vertical mount integrated HIMALAYA PRO DAC and headphone amplifier. It is priced at $799 SRP.
Disclaimer: This sample was sent to us in exchange for our honest opinion. Headfonics is an independent website with no affiliate links or status. We thank the team at HIFIMAN for their support.
To read more about the HIFIMAN products we have previously covered on Headfonics click here.
Note, that this post follows our current scoring guidelines which you can read up on here.
When HIFIMAN released the EF400 Himalaya R2R equipped DAC / amplifier combo it was received with applause by many and it marked a new chapter for HIFIMAN in my opinion.
The reason for that is that It seemed that at that point in HIFIMAN’s history, they revved up the engines and launched more products in one year than ever before.
To give the statement validity, HIFIMAN followed up shortly after the release of the EF400 with the EF600 desktop amplifier combo, again, in the same year.
My initial thought was that hopefully there were enough differences between the two so that the market would not undersell one or the other because they’re both worthy components.
However, with a recent EF400 price drop, the EF600 stands tall, no pun intended, because it offers additional Bluetooth connectivity plus more power on tap amongst other features justifying the higher investment cost.
Tech Highlights
Let’s go over the works. For the EF600, HIFIMAN used a pair of custom HIMALAYA PRO R2R chips developed for HIFIMAN exclusively. It makes a strong statement when a company uses proprietary components at this level.
HIFIMAN claims that these HIMALAYA PRO chips beat the popular PCM1704K chips specifically in distortion levels, and noise levels, with very low power requirements to boot. But the unspoken musicality aspect was left out and perhaps the Himalayas outperform in that as well.
The DAC section circuitry feeds the amplification circuitry through a switch that operates the source and that feeds into a buffer stage to then go through a low-pass filter circuitry. At that point, it jumps over to the 4-channel attenuator or volume knob.
The DAC section includes two digital filters to choose from which are selectable upfront. There’s a non-oversampling and an oversampling mode. I left mine on non-oversampling and high gain most times during listening sessions.
Digital Formats
There’s a current trend of manufacturers making DACs that are strictly PCM and the HIFIMAN EF600 follows suit offering PCM at up to 32-bit at 192kHz and nothing else.
I suggest going to HIFIMAN’s website because they posted an ASIO driver for the EF600. And although the EF600 worked as a plug-and-play device out of the box, these drivers might help some.
In my case, I did not notice any improvement, perhaps the improvement was added stability which is hard to pick up on.
So, after mounting the driver, I put the EF600 through some hard tasks on my PC and this DAC section seems to have lots of raw processing power.
I ran multiple sources to see if the DAC would break down but it was constantly coherent. These HIMALAYA PRO chips do complex multilayer audio processing effortlessly.
Amplifier Section
HIFIMAN boosted power output, comparatively from the EF400 to a formidable 5.12 watts per side on the balanced XLR 4-pin connector upfront and 1.8 watts if you go single-ended.
The amplification circuitry looks similar on both models and both use a dual mono circuitry design. The real-world available power output seems conservatively rated to my ears, however.
Now, take a look at the enormous Oxygen-free copper wire wounded toroidal transformer coil at the bottom of the unit feeding that amplifier section. I see those most of the time on subwoofer plate amplifiers and such but not on headphone amplifiers except for some high-tier models.
This component which is mounted on the bottom portion of the chassis also keeps the weight of the unit and center of gravity at the lowest point and this makes the cabinet bottom heavy. This adds stability to the large, erect structure.
There’s a two-stage gain selectable upfront but you might find a small reduction in dynamics on low gain compared to the high gain setting, I did. But regardless, the volume knob raises the volume slowly you could use the high gain most of the time.
Design
It seems HIFIMAN had some specific objectives in designing the EF600 besides placing most of the weight at the bottom.
They also thought of heat dissipation and top-and-bottom vented the cabinet so that convection cooling could naturally occur within the unit. HIFIMAN designed the EF600 to be erect so it can also serve as a headphone stand.
One small observation I want to mention is that due to the heat produced by the EF600 up on top, I would suggest shutting off the unit and allowing it to cool down before you sit your headphones on the built-in stand to prevent possible damage to your headband and pads.
The overall cabinet size is massive and it sits atop my desktop as a Monolithic structure, it captivates and requires your visual attention. The Bauhaus collaborated design is made from a vintage quality thick aluminum plank, folded into a U-shaped cradle, and finished off with a polymer centerpiece.
One aspect I wasn’t too keen on was the volume knob itself. Aside from it appearing similar to a professional cooking stove gas knob, there’s an unusual amount of play in that shaft. HIFIMAN should have used the same one they used on the EF400 is where my mindset is.
The overall design is old-world rugged, to say the least. There’s a rocker switch above the volume control that scrolls and adjusts gain levels plus it also sets the input source. Eight small LEDs indicate if the unit’s on high or low gain, what filter is engaged, and the source selected.
IO
Connectivity-wise, there’s a give and take here. The EF600 lost a couple of ports upfront but gained a digital coaxial input. It did retain the two USB inputs but aside from that you also gain some analog inputs.
You get two ways of connecting headphones on the front panel, one is a full-sized 6.35mm jack along with a balanced XLR 4-pin connection. I miss the 4.4 Pentaconn connectivity here in particular. You can always use an adapter to gain 3.5mm connectivity.
The EF600 has two analog inputs on the back panel. One set is a conventional RCA red and white jacket input type plus there’s a balanced set of 3-pin XLR input connections.
The same connectivity is there to access the DAC section in the form of a couple of outputs. So, the EF600 I/O features let you access the amplification section separately and the DAC section as well. The connectivity here surely surpasses that of the EF400.
One thing to note is that the outputs are fixed. These outputs are, however, affected only by the selectable digital filters but not the gain or the volume knob.
Bluetooth
While there is a comparative lack of connectivity upfront on the HIFIMAN EF600 and perhaps one could say the same about the compatible digital formats that are playable, this model evens the score by adding Bluetooth support that can play friendly with a plethora of BT codecs.
Amongst those compatible are Sony’s LDAC and Qualcomm’s aptX HD on top of the more common SBC, AAC, and plain vanilla aptX. Now, I suspect that the BT setup inside the EF600 uses a 5.2 radio but I could only verify it to go up to 5.0, and also made me realize I need to upgrade my mobile devices.
Regardless, I had nothing but good times with this BT section implementation since it’s easy to pair, and stays locked onto the source well.
But most of all, the sound quality was on par with some of the best BT receivers and surprisingly good when receiving an LDAC source from my humble mobile phone.
Packaging and Accessories
The EF600 comes in HIFIMAN’s new packaging which is constructed of brown corrugated cardboard with a product laminate on top. This is fine with me. Inside the flip-top box, the EF600 sits inside a large custom foam mold along with the power cable and the Bluetooth antenna.
There’s no literature but the unit is rather simple to operate and you might not need instructions. But a reference source would have been nice along with a quick guide and some more in-depth specifications.
Our listed specifications were copied from the box since I could not find much detailed information elsewhere.
Sound Impressions
To test the HIFIMAN EF600 I mostly used their in-house-branded headphones. The Arya version 2 plus the Organic variant were used. The Audivina was also used for a closed-back perspective.
The OG Sundara was also used briefly plus a couple of their top-tier IEMs, particularly the Svanar and RE2000 Gold Edition.
Summary
There’s plenty of pep on tap on that EF600 knob and the smooth action produces a slow but steady volume level rise. This amplifier and volume control combo operate closely in general characteristic to a well-broken-in class A amplifier in that the first portion of the volume control doesn’t reach loud levels.
But once past 10 O’clock, there’s an ample volume amount that will satisfy any ears and simultaneously comply with supplying enough power to operate some difficult-to-drive loads. So, in general, you get a slight warmth from the amplifier fed by a dynamic DAC section that effortlessly translates those bits into notes.
The DAC section sounds fluid and seems to retain micro harmonics captured in certain tracks that some DACs miss in reproducing. In combination with the Organics, I can hear an extra layer and dimension to Carles Benavent’s bass playing on “The Ultimate Adventure” for example that I rarely hear with other setups.
The midrange also displays similar characteristics and the combo just sings along in a natural tone. There’s an ample amount of forwardness to details but not an overcooked amount plus it seems to tame highs well without over masking their presence.
Staging and Dynamics
The HIFIMAN EF600 projects subsistence along a healthy, and meaty musical presentation that demands attention accompanying its looks. It produces a sonic performance level which is of high caliber for the price range this model sits at.
The EF600 is rather powerful and has a lack of shyness, so it tends to sound punchy, dynamic, and onward marching especially if you use a fast responding planar. Transient response is fast and propulsive.
Click on page 2 below for our recommended pairings and selected comparisons.
