Thank you to Hifiman and Tyll for the loaners. You guys rock.
The equipment used for this review include: The Hifiman EF-6 Amplifier, HE-6 and HE-500 headphones, The Audeze LCD-3, Bottlehead Crack using a 5998, Aune T1 USB Tube Dac using a Telefunken 6922, Epiphany Acoustics and Kimber RCA cables and lastly my AudioEngine A5 Home Speakers.
Prelude to Bliss
If Darth Vader were an Audiophile, the Hifiman EF-6 would be his favorite Amplifier. This no mess, no fuss brushed aluminum and steel design is rated 5 watts Class A per channel with an MSRP of $1599. Now that’s power if I ever saw it, it was specifically designed to drive the power hungry HE-6 Planar Magnetic Headphones. From top to bottom, every curve and angle is both stylish and menacing in the most elegant fashion. At 13 inches x 12.2 inches x 4.1 inches ( 330mm x 310mm x 105mm ) and tipping the scales at 24 lb ( 10.75KG ) she definitely has quite a great deal of mass. But, it isn’t the size that counts…it’s how you use it.
The Class A Circuitry boots up in just a few seconds and provides a constant and steady stream of audio from beginning to end. Audio can be transmitted clearly and effectively within just a few seconds of turning the amplifier on and will cut out quickly with no decay when you decide to press the power switch. No long boot up or warm up time needed here. Crossover Distortion is minimized to barren levels as well, due to the effective implementation of the physical layout of the Amplifier itself: It avoids some of the messy problems found in common A/B push-pull devices. It also stays relatively cool in comparison to the Schiit Lyr, which gets too hot too quick. By comparison, the EF-6 won’t win any Ice Skating competitions but it certainly is much less warm after an hour or so of usage side by side with the Schiit Lyr. Solid State Amplifiers naturally tend to generate heat and with 5watt output I had expected the EF-6 to be comparable in heat output to the Lyr. I was happily surprised to find this is not the case, she runs noticeably cooler.
Current bouncing around is avoided due to a brilliant internal layout. It is efficient in terms of energy transfer ( It is a Class A Amplifier, this doesn’t mean it is an efficient amplifier in terms of DC current In and out ) and in turn reduces capacity coupling issues. Basically, this means the amplifier sounds clear and as distortion free as possible. There is no signal or electrical interference caused by voltage inside the circuitry itself, everything flows nicely and is properly laid out to flow into the output device. There is a 160 VA Transformer unit inside and a CLC Filter as stated by the manual. This equates to massive output power. I am not going to open her up to check. Of course, it isn’t like I don’t trust it. I’ve already seen images of it and really do not feel comfortable unscrewing the top plate just to snap a picture. I don’t want to put a scratch on this baby…not one! So, if you would like to see the internal layout, please use an Internet Search engine and try to find some snaps taken by someone else. There are 10 screws on the top side of the brushed plate and I have no desire to accidentally scuff anything up…it’s just too beautiful to leave that to chance. Hifiman says the Attenuator is hand made and that the resistors are all hand selected.
The face plate is made of a gorgeous acrylic material and houses four buttons
( Power, CD/AUX/Line In with accompanying blue LED lights ) The titanic volume knob, a standard 1/4 output and a 4-Pin XLR output. I am elated to report the ease at which I can swap between sources with the simple press of one button on the face plate Should I want to stop listening to my Music via my Dac that is fed to the proper output channel section, all I have to do is tap the corresponding button on that face plate to engage another source. Such as my TV. Swapping between two potential sources is sublime but what really impressed me was how clear and clean each swap is. No loud pop or sudden CRACKLE. Just a clean switch over to the next source of your choosing. The rear side is nifty and everything is again well laid out and formatted for easy usage. RCA inputs for each source that are color coded in white and red, as well as the same RCA’s for one Output to be used as a Pre-Amp. There is also a voltage selector which I recommend you never touch or switch from stock mode, as well as a simple Gain switch: High and Low. For most applications the Low switch is more than sufficient for easily driven audio products. I recommend the High Gain mode only for blisteringly hard to drive Headphones like the HE-6 / HE-4 or similar inefficient headphones that require a small Nuclear Reactor to power.
I have been through exactly 9 different Hi-Fi Solid State Amplifiers this year alone, ranging from a number of different companies. The EF-6 is the 2nd cheapest one of the lot and happens to be the only one I want to keep for myself. This amp makes me happy and I feel the EF-6 to boast serious value for your dollar. It’s worth every penny and more and I really do not want to box this back up and ship it back to Hifiman. Quality had nothing to do with the other amplifiers I have tested or reviewed. For others, I am sure any number of the other high end/end game amps suited their preferences. So far, nothing solid state has made me happy except this EF-6…and it is one of the cheapest at $1600 that I have gotten on loan all year. That is really saying something. But, this doesn’t at all surprise me. I hunt specifically for well rounded audio products to keep as my own. If it isn’t well rounded to my ears, I never keep it or try to purchase it after my time with the loaner expires. In this regard, I feel the EF-6 to be exceptionally well rounded in terms of genre selection. However, being the deal hunter that I am, I tend to gravitate for Amplifiers that give me some simple EQ options. I might be asking for too much, but I would have preferred to have a simple Bass and Treble Dial. Maybe Hifiman’s next expensive amp can bring some physical EQ knobs so I don’t have to resort to modding my source or using Foobars lifeless Bass functions. If Cowon can offer such a great EQ function with their portable daps, Hifiman can certainly add some simple Bass and Treble wheels on the amplifier itself to better customize your experience with High End Headphones. I’d like to see them go above and beyond in their next amplifier that is on this level.
The overall presentation qualities are middle ground. In combination with what it was made for ( the HE-6 Headphones ) the end result is a very relaxed experience. Not too distant, not overly forward. One thing I find lacking would be the sound staging qualities. While not particularly wide or transparent, it is still more than great for all of the non-sound stage oriented Orthos out there, or for any headphones that are not sound stage oriented. Clarity is phenomenal. Vibrancy is stellar. This amp does exactly what it was intended to do, which was drive the HE-6…and boy does it do it well. It is a fairly neutral sound due to it handling Audeze House Sound and Hifiman House signatures extremely well. You’d never be able to tell his was a “Hifiman Amp” just by the tonality alone. It is extremely well rounded.
The volume knob makes me smile every time I use it. It has a hefty amount of weight to it and feels like a solid chunk of metal that gives a satisfying clunk every time you dial it up or down. The same feeling you would get when tapping a heavy piece of metal on something. It screams quality and reminds me of that scene in Back to the Future were Marty dials Doc’s giant wall sized speaker up to 11, plugs in his guitar and literally blows himself back 20 feet, ultimately destroying the entire room. Of course, nothing like that happens with the EF-6. ( Only in my mind ) Each of the buttons are loose feeling, if I had one gripe about the physical qualities this amp has, it would be the small power and channel swapping buttons. They jiggle a bit and are not as nice feeling as the volume knob. I’d have loved to see them offer similar quality, but this is a minor gripe as they are still metallic. ( Maybe Touch Screen UI is the way to go in the near future? )
I asked Fang what his thoughts on the Future of Hifi Audio were. His reply was a shocking step away from everything the EF-6 is about:
“I think the future of hifi audio should be portable hifi. We will keep working on our portable players and headphone/earphones.”
I tend to agree with him. When I reviewed the Audeze LCD2 on Head Fi a while back, I was met with 40 pages of users blasting me and raging against me for saying these large and inefficient sets being produced lately are a step back. I am honored to see such an authoritative and brilliant figure in Audio share a similar view as mine. I also asked him what the design process of the EF-6 entailed and was again shocked to hear this:
“We designed this amp for the HE6, one of the lowest efficiency headphones in the world. We made four versions in almost 2 years, and finally decided to use the current design because it can provide the highest output and the best musical tone. “
Gosh. Only four versions? This is a guy who knows exactly what he wants and when he sets out to accomplish his goals, he really nails it on the head quickly. This is what I love about Hifiman. I like to think of myself as good friends with Hifiman in general, especially with Peter. We chat back and forth often and they handle all of my questions or requests quickly. They gained my undying respect for years of loyalty to their buyers, they act on every problem mentioned and are quick to fix it. Mr. Fang and Peter, you both are just too awesome for words and I cannot thank you both for the happiness you have provided me with, but more importantly for your friendship over the years. You guys rock!
High End Ortho Impressions on the next page…
I think you liked this one. Just a gut feeling.
Yep I got the same feeling too.
Ok, how do we switch jobs?? This is like being a test driver for Ferrari. Great job but lets not pretend like you didn’t enjoy this one a little more than most eh 🙂
Outside of the Apex Butte and Bottlehead Crack, this Hifiman EF-6 is the only amplifier I’ve ever come across that I actually lusted for.
I’m unpaid. I do this out of love for everyone. I don’t make a single cent. 🙂
Question, have you guys ever tested the Hifiman EF2a Tube Amp/Dac combo? It’s in the same wheelhouse as the T1 and for around the same price or less. It’s a great looking little tube amp but I’m curious about how it preforms compared to the T1
You told that you used the Aune T1 in this test.
Could you tell us more about this little DAC / amp ?
Does it worth it price ?
Thank you in advance,
Sure. I upgraded to a Telefunken 6922 ( $150US ) and the result over the stock tube and $10 upgrade tube is significant. It is a light and airy Dac. It can be used as either a USB Dac or in Amplifier mode, RCA in and out potential. Clarity is good by itself and I was surprised it has enough output power, 1mw output into 32ohm. One of the most spacious DacS I’ve come across. Sound staging is the Dacs best feature.
Aune makes some great Schiit. Definitely worth the price. I am going to compare it with the new Schiit Modi and Fiio Dacs very soon.
I wish I had a reason to buy the Modi…
Meh, I’ve not heard it yet so I can’t judge.
Omgosh I want one!
I have not gotten a chance to hear the Soloist yet, so I cannot compare. Maybe one of the other guys can help with that. But, I found the EF-6 to be extremely well rounded due carrying Hifiman AND Audeze house signature without any problem. Normally, you don’t find Amplifiers that can present an HE6 and an LCD3 they way they should be presented, usually one side takes a hit somewhere. Some quality lacking or “better on another amp”. I have no reservations about that at all and found Audezes to sound like Audezes should, and Hifiman headphones to sound like Hifiman headphones. That is not too common. A great neutral amplifier is needed for that, one that lacks coloration so it can let the headphone flavor handle itself without being saturated by the flavor of the amp.
On low gain mode, the EF6 made my A5 speakers sound so good…
I wonder how this compares with the Burson Soloist?
Looks like a great amp! I may have opted for a higher end volume pot instead of a stepper but that’s just me.
The review however contains some silliness.
First of all- solid state devices by themselves aren’t too prone to give off heat. Heck- any mechanism that doesn’t operate at 100% efficiency will most likely give off heat, noise or other means of “energy exhaust”. If you want extreme heat- take a look at tube amps that are also valve rectified. The mode at which they need to operate needs deliberate heating.
Secondly- “Crossover Distortion is minimized to barren levels as well, due to the effective implementation of the physical layout of the Amplifier itself: It avoids some of the messy problems found in common A/B push-pull devices.”
How does crossover distortion occur in a device that’s operating in class A? If it does- how efficient layout can reduce it?
Thirdly- “Current bouncing around is avoided due to a brilliant internal layout. It is efficient in terms of energy transfer ( It is a Class A Amplifier, this doesn’t mean it is an efficient amplifier in terms of DC current In and out ) and in turn reduces capacity coupling issues. Basically, this means the amplifier sounds clear and as distortion free as possible. There is no signal or electrical interference caused by voltage inside the circuitry itself, everything flows nicely and is properly laid out to flow into the output device. There is a 160 VA Transformer unit inside and a CLC Filter as stated by the manual. This equates to massive output power.”
Ok, this makes me go all like Jackie Chan at that one meme picture.
What electrical phenomenon are you referring to as “current bouncing”?
What is meant by “energy transfer”? I mean sure- no energy can be lost in the amp, but a class-A amp has one thing it does with utmost efficiency- space heating! Sure, space heaters by themselves are one of the most efficient electric devices but at 0W output a class-A circuit is a ~100% space heater. At full blast efficiency of class-a circuits range from 12-50% with the rest converted to heat. Now try to think how much of the time will you be driving the amp at full power and you should have an idea of how much energy you might get heat wise.
P.S. There are actually two transformers inside the case. That is something that makes the whole thing smell high-end. Very few headphone amp manufacturers do separate power for input/output stages and not that many separate power for digital and analog circuits.
P.P.S. This might actually be one of the better amps to come out this year. I congratulate Hifiman!
– Everyone wanted a comparison with the Lyr, which gives enough heat off to actually cook on its surface. I thought it was worth mentioning.
-The EF5 has a hot swap button for three device sources. There is no crossover switch distortion when switching over to something else. Efficient layout is immensely vital to reducing noise. I am not sure I follow you on that question, it kind of answers it self.
-The physical layout is like a race track. Circuit pathways are nice and clean, meaning the electricity inside the amplifier is not zig zagging between the parts inside. Its a nice straight design. In crappy amplifiers, transistors, connection points and other pieces often flow past one part, around another and into something else. This is how computer mother boards work, except in cases of very nice and expensive boards where things are actually designed properly. Example: A>B>C>D>E>F>G with each letter representing a part of the circuit board and voltage running through each piece in a nice straight fashion with no deviations around another piece. Where as other boards that are cheap look like A>G>B>C>F>E>D with a connection from A to B, B to C that run physically around G. An example of Bad design.
-You kind of answered your own question on the efficiency bit. Class A amplifiers are not efficient in taking voltage out of your wall and into the device. By Efficiency in that point in my review ( as I mentioned ) I was taking about the physical layout and how nicely everything flows from the input to the output device.
-All electronic circuity puts out an electromagnetic field that can cause distortion to other circuitry near by. Hifiman did a great job in lessening that potential and its very impressive when some amplifiers with this type of high output can stay so quiet despite having 5watts running through it.
-It definitely is one of the better amplifiers to come out recently. The low end response is immense, 3 source swapping, extremely well rounded in terms of sonic qualities. I cant name an amplifier that can showcase the T1, LCD3 and HE6s presentations and tonalities without significantly ruining something. I’ve not come across a single amplifier that could do that. It is crazy-neutral and potent on the low end. Something I have always wanted, a no mess no fuss amplifier that caters to ME instead of me catering to it. What other amplifier can do the LCD3 justice, the HE6 justice, the Beyer T1 Justice and pretty much everything you use with it? Its just an awesomely well rounded piece of equipment.
ugliest picture I’ve ever taken