Review: Hifiman EF100 – The Hybrid Amp

The EF100 has more than enough power and it drove all the orthodynamics I tried on it with ease. Left/Right balance is pretty good but it isn’t the most 3-dimensional sounding amplifier as positioning isn’t that good. Sound stage width is pretty good but it doesn’t have a lot of depth.

While the overall detail retrieval is OK, it – just like the layering – could be better. I’m missing a bit of timbre and emotion in the mid-range and I wish the tube could have added that tad more smoothness and musicality. The EF100 clearly is a linear and neutrally tuned amplifier and it doesn’t emphasize anything in particular. In that regard it’s perfectly normal I’m missing the extra smoothness of course, it just wasn’t tuned like that. It’s fast and tight and it is more solid state than tube sounding but the effect of the tube certainly is audible. Unlike Hifiman, I wouldn’t call the EF100 warm and smooth sounding however. The EF100 at the same time sounds spacious and it has just the right amount of air in its delivery.

Bass is tight and fast and like everything else is on the neutral side. It doesn’t have that big body and you won’t get any deep bass rumble. It’s always very controlled but there’s no depth. Same more or less goes for the mids section. It’s perfectly in line with the bass and it never upsets. The tube adds just the right amount of magic to give the mids their musicality. I’m repeating myself but I don’t find the mids to be particularly detailed or layered, the timbre is lacking a bit. The highs are completely inoffensive and aren’t the most extended.

I appreciate the EF100’s linearity, spaciousness, neutral tuning and its transparency but on the other side I’m mostly missing detail, depth and timbre in its sound throughout. It kind of leaves me with mixed feeling but you can’t forget the EF100 only costs $499/400€ and it finds itself on the lower end of Mid-Fi. In its segment the EF100 certainly doesn’t disappoint.


Hifiman puts the output impedance between 32 and 300Ohm and with [email protected], the EF100 should be especially good for orthodynamics. The first ortho I tried was the Audeze LCD2.1 and the magic just wasn’t there. The LCD2 sounded lifeless which kind of surprised me as the LCD2 easily sounds good on a lot of amplifiers. Completely different and logic story with the latest Hifiman orthos, the HE400i and the HE560. It’s clear the amplifier was developed with these units in mind and the EF100 makes them sound good. I especially preferred the HE560 on the EF100, it drives the headphone effortless and the neutral and fast tonality of the EF100 matches perfectly with the HE560’s characteristics.

The New Audeze EL-8s are a far better match with the EF100 amplifier but still nowhere near the EF100 – HEXXX Hifiman pairing. I haven’t made up my mind about the EL8’s yet. They are supposed to be easy to drive but the volume button on the EF100 had to go up considerably. Sound wise I was mostly missing some body in the EL8s when using the EF100, it seems the EF100 & Audeze pairing isn’t the right one for my ears.

Surprisingly I liked the 300Ohm dynamic driver HD650 on the EF100. You get a faster, tighter HD650 where the so called veil has been lifted and the tube just adds enough to make it a musical and slightly warmer sound. It’s a quite good match and I fully recommend it to those who find the HD650 to warm and smooth sounding on an OTL tube amp. With another dynamic, the low impedance 32Ohm Beyerdynamic DT770 AE, the EF100 performed good as well. I still prefer the AE on a warmer sounding amp where it gets more bass though. The EF100 makes it a more neutral sounding headphone with a little less body in the mids. The highs stick out more and that sometimes makes the treble a little hot. But all in all a pretty good match: clear, fast and tight. Just like the EF100.

I started my IEM test with my most hiss sensitive custom, the Legend R. It picks up only a very little amount of noise when no music is playing and with the Legend R that means the amp is really silent. The problem I have with my customs is that even one click on the volume dial is already louder than I’m comfortable listening to. If possible you could of course decrease the output volume of your source but I have to conclude the EF100 isn’t the most appropriate amplifier for sensitive multiple balanced armature earphones.


The Hybrid EF100 goes for $499 or 499€. The amplifier, sound quality wise, is situated in Mid-Fi to me. Its tuning is fast, tight, clear and transparent and the 6N3J gives it just the right amount of warmth and smoothness. Do note the EF100 is not at all a warm sounding amplifier, it leans way more to the solid state side. The EF100 in combination with the Hifiman headphones and even the dynamic ones sounds musical and precise. What I am missing most in the EF100 is more detail, layering and timbre but for the price the EF100 is selling, it surely sounds more than “correct”. A higher level sound would cost a lot more money and price quality wise the versatile EF100 scores big. No doubt about that.

The EF100 is small in size and works as a DAC, headphone amp and speaker amp. It’s an excellent headphone amplifier for a beginner setup, an office setup or a second setup like for on your night stand. If you’re a fan of a natural sound, neutral tuning and want to take the first steps in to the wonderful world of tubes, the EF100 could be the amp for you.

The EF100 can be bought directly from Hifiman via their Head-Direct shop or one of their official dealers. Those who have read this review till the end get a scoop: we will be doing a Hifiman giveaway next month (June 2015), keep an eye out for it on our Facebook. And don’t forget to rate this review, please.

3.6/5 - (153 votes)


Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply May 26, 2015

    Anthony Kimball

    I was wondering if this amp would play nice with the Oppo headphones…It might play to their strengths.

    • Reply May 27, 2015

      ohm image

      That’s an interesting question. Being now an owner, I’ve got to say: hmmm, interesting.

    • Reply May 27, 2015


      If the OPPO needs a fast, tight and clear amp, then yes

    • Reply October 9, 2015

      kindergoth sissygeek

      Was satisfied but not excited about my Oppo PM-1s. Wonderful build & comfort. But lacking in dynamics and excitement: and (ordinarily) I’m fond of a laid-back sound.

      Switching sources (from Linn to Primare) meant I no longer had 2 analog outs. Had to use a digital S/PDIF cable between the Primare CD and my HeadRoom Portable Desktop headphone amp. The Oppos felt far stronger, immediately.

      The background went from quiet to perfect silence. That–and its versatility–being the reasons I’ve relied on the HeadRoom all these years. (No experience with the EF100; sorry.)

  • Reply May 3, 2016

    Brad Guzman

    Do you lose quality by using a different DAC going through the CD input?

    • Reply May 3, 2016


      lose or gain

      • Reply May 3, 2016

        Brad Guzman

        Lose, sorry I’m just getting into this stuff.Iin the review he said he used the HERUS and bypassed the internal DAC. So I guess my real question is how he did it? Seems like the only way to achieve that would be to have the HERUS input through the CD input of the amp.

        • Reply May 4, 2016


          You can’t do DAC twice. But if you pass along a digital signal without damaging it somehow, the DAC (or final DAC?) should be the only DAC conversion that matters, since it does the bit alignments.

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