Saturday, June 02, 2012

Review: FiiO E6

EDIT 16.01.2013: I´ve received a FiiO E07K a few days ago and the experience I made with it prompted me to alter this article. I´ve therefore updated / changed it considerably.

I bought the FiiO E6 in November 2011 and since then this tiny, little headphone amp has made me extremely happy. I´ve always loved its pleasant sound. Some weeks ago I started to think about this and asked myself: "Why do I like its pleasant sound so much? Should it really be this pleasant? Is it really neutral?" Should you be a faithful follower of my blog you already know that I´ve been using it for almost every review I´ve written for this blog, I´ve used it for my portable CD players, I´ve used it for my Sansa Clip+, I´ve used it at home, I´ve used it when I was outside, I´ve occasionally even used it with my ASUS Xonar Essence ST. The FiiO was the only thing during those months that was able to make me truly happy without showing any flaws whatsoever. And that´s where I have been wrong because it sadly colours the sound, neutrality really isn´t an advantage it has. My original conclusion to this article was:
"By now it should be clear to you, dear reader, that you won´t necessarily need an ultra-expensive headphone amp in order to experience sonic bliss, the FiiO E6 will do just nicely with headphones ranging from 32 to 150 Ohms. You shouldn´t trust someone who describes the FiiO being inferior to other amps because of its low price. I cannot imply you to buy it, you have to make that decision yourself. Will you like the additional little box attached via another cable to your portable player? I myself don´t mind but what about you? I´m afraid you have to find that out on your own. You might be in for a sonic surprise, a surprise you maybe won´t like: bass you were expecting from your iPod may now be absent just because the problem of mismatching output impedances has disappeared. In my opinion however you should try it out anyway, $ 25 won´t really hurt and you might be eternally rewarded with something you´ve never experienced before with portable players: almost perfect neutrality, nice design and more gain than ever before."
To reach this conclusion I´ve beforehand spent precious time on explaining what a headphone amp is, gave examples why you won´t need a costly headphone amp, why the FiiO E6 would also work for a headphone as expensive as for example the Beyerdynamic T50P... blablabla. But everything changed with the arrival of the FiiO E07K: To review that headphone amp / USB DAC I wanted to find out how it would behave against a reference, something that appeared to be impossible for me before. When I wrote the original review for the E6 I couldn´t think of a method to reliably compare it to an ideal reference and I´ve always hated that I seemed unable to find out how it really sounds, if it colours the sound, if it introduces errors... when all of it could have been so easy.

FiiO E6

This feeling of being unsure about my rating for the E6 and the aforementionend original conclusion has been nagging me since publishing this article in June 2012. But now I´ve found a way to come close to an objective-as-possible review. My E-MU 0202 USB broke down during the last days of December 2012 which has robbed me of my basic ingredient for my testing methodology. It not only forced me to devise a new method for comparing units like portable CD players to my reference files, it also prompted me to alter my testing chain for such an occasion so that I could finally perform listening tests with headphone amps. The solution for latter cases was the Creative Soundblaster X-Fi HD USB: by recording its lovely output with my ASUS Xonar Essence ST I would create a new reference against which the FiiOs would have to be compared. Therefore my usual reference files for the FiiOs wouldn't be the sources for the testing material themselves, instead I´d use the playback from the X-Fi HD recorded with the Essence ST. After that I would insert one of the FiiOs into the signal chain between the Creative and the ASUS to record the same material again. Have a look:


Creative Soundblaster X-Fi HD USB -> ASUS Xonar Essence ST = Reference files

Compared to:

Creative Soundblaster X-Fi HD USB -> FiiO E6/E07K -> ASUS Xonar Essence ST = FiiO results

Having done both steps I now would be able to compare the results from the FiiOs to my reference files. The sonic characteristic of the X-Fi HD USB embedded in the reference files would ideally be completely retained by the FiiOs and in case they´d colour the signal it would be incorporated as well. There are some obstacles which again might colour the results: the line-in of my Essence ST is electrically not comparable to a headphone which is what the FiiOs were designed for in the first place. From what I´ve read a line-in is a much easier load for a headphone amp than a headphone with an impedance of for example just 15 Ohms. Which means that when one of the FiiOs is driving the line-in of the Essence ST it could theoretically be 'easier' to 'hide' possible colourizations. But I nevertheless think that this method enables me to reliably spot differences compared to unplugging/plugging headphones from one amp to the next. To do it this way also made it feasible to create crude measurments; I wanted to see how these would compare to the professional measurments NwAvGuy did for his wonderful article about the FiiO E6.

FiiO E6 from below
To shorten this article I´ve partly removed the long & boring explanations about headphone impedances, gain and possible advantages of having an extremely low output impedance. Some of those sections can now be found in the article about the FiiO E07K; albeit shortened much. Reason: there are much better articles to be found anywhere else, much better than I could ever write them. Just a few words about the features the FiiO E6 offers: its high input impedance gets rid of every impedance mismatch error a headphone amp can possibly produce. It sports an output impedance of just 0.25 Ohms (according to NwAvGuy´s measurment) which should be perfect for any headphone and certainly doesn´t pose any problem for my Sennheiser HD-448 or my Superlux HD-668, even though these aren´t very susceptible to high output impdances anyway. I bought the E6 to rid myself of any possible impedance problem I could ever encounter with portable players. For example: most of the headphone amps inside my portable CD players or MiniDisc recorders have a fairly high output impedance and other obstacles not advantageous for good sound. Then there is the amp inside my X-Fi HD USB which supposedly has an output impdance of 36 Ohms and the one built onto the Xonar Essence mainboard (11 Ohms) - both are not suited for difficult IEMs. Connected to their headphone outputs the FiiO E6 simply renders this problem moot. But this tiny headphone amp can also be used with line-outs from stationary sources, for this purpose it is equipped with a special low-gain setting (2 Volt mode). However, you might run into problems should you be using it with one of those louder-than-usual sources I described in this article: instead of the quasi standard 2.0 V (which the FiiO adheres to) they sometimes output with 2.2 or 2.5 V, supposedly leading to severe input distortions when used with the FiiO. But now off to my own measurments and audio rating, yes?

FiiO E6, 1 Volt Mode (High Gain)
FiiO E6, 2 Volt Mode (Low Gain)

FiiO E6, Total Harmonic Distortions, 1 Volt Mode (High Gain)
FiiO E6, Total Harmonic Distortions, 2 Volt Mode (Low Gain)
FiiO E6, Intermodulation Distortion, 1 Volt Mode (High Gain)
FiiO E6, Intermodulation Distortion, 2 Volt Mode (Low Gain)
Click on one of those pictures and scroll trough them using your mousewheel, you´ll find that differences between them are not that big. In low gain mode the FiiO does have less high frequency distortions but I really don´t know if they´re audible or not. But low frequency distortions seem pretty strong to my layman eye, these could be responsible for its pleasant sound by adding something that doesn´t belong there. Everything else looks fine though, especially when you consider how small this amplifier is and that it is selfpowered - there must fit a battery somewhere into the small case. What I couldn´t find however was the overload problem NwAvGuy described in his article about the E6... strange. Well, I have to consider the possibility that my X-Fi HD USB simply isn´t loud enough on its line-out (I have to change the volume by +2.5 dB after recording anything that has been played back by it if I want to have 0 dBfs) to distort the input of the FiiO. It´s also possible that his unit behaved a bit different, who knows.

FiiO E6 power/EQ/voltage mode button
At this section you formerly could find sentences like "...seems to warm up the sound ever so slightly (...) sometimes it sounds a tad boring...". Being now able to compare the FiiO to my reference files good and proper I have to say that those sentences have been the understatement of the century because the biggest problem of the FiiO E6 are dynamics. It removes much of the impact transients have, bass punches disappear into nowhere and high frequency attacks loose their bite. This is very evident when the FiiO-derived results are compared to my reference tracks from The Girl with the Dragon Tattoo or Episode II soundtracks; both show an extreme amount of very high frequency attack diminished quite a bit by the E6. Deep bass impact is decreased as well, all of this reduces the impression of dynamics, snap and punch. Madonna's track "Skin" sounds mellower than usual, its timing is noticeably slower when amplified by the FiiO. Well, at least speed is reduced consistently throughout the whole frequency band. People call this lack of dynamics a 'laid back' sound, I call it wrong. Resolution and definition are other areas where this amp fails: cymbal hits by an orchestra are close to being reduced to simple noise, the characteristic noise of a bow striking the strings of a violin quite audible on the reference tracks sounds unintelligable through the FiiO. Rendering the depth of a virtual stage correctly is equally problematic because it flattens the stage considerably, the impression of a holographic recording disappears. On the other hand, sonic balance and character of a recording are retained decently. While deep bass and highest frequencies are diminished, this isn´t very noticeable because it is compensated by adding a small amount of upper bass even though this also thickens up frequency areas that shouldn´t be thickened up. This is very audible on the organ recording I always use (Vierne, Michael Murray)... in fact, the organ almost sounds as if having distortions (there are none of course on my reference files). I´m very sorry but here are my reconsidered ratings for the FiiO E6:

Sonic Balance:
Stage / Ambiance:

FiiO E6: black beauty
As it turned out in the end people deriding the FiiO for sounding boring were right - but I wouldn´t see it. Maybe because I didn´t want to or because I lacked a convincing method for comparing it. I´m not ashamed to rectify this error but have you noticed how many of my articles have been rewritten recently? First the one about the X-Fi HD USB, then the Sansa Clip+ and now this one. And then the articles about USB cables which in hindsight feel like a hoax... I really have to be more careful in the future when reviewing some audio gadgets. I have to measure what I can measure and I have to get rid of any error that could possibly happen. And I have to find and maintain valid methods for objective comparing before I´m writing a review. Anyway, sonic signature of the FiiO E6 is not as disadvantageous as it sounds because it can be used to create exemplary synergy effects with audio players or headphones. Take my Sansa Clip+ for example: combine it with this FiiO to achieve much more gain and you´d have a balanced sound you wouldn´t expect when listening to the Clip+ alone. The explosive dynamics of the Clip+ are a perfect fit for the mellow sound of the E6, its sonic disadvantages will compensate the ones from the FiiO. During the last days I´ve tried this combination and it indeeds sounds very well. Besides: both of them are tiny and don´t cost much. On the other hand, a combination of the FiiO E6 and the Sony NW-A 1000 has to be avoided; you´d drown in mellowness and boredom. This little amp would also be a good choice for overly dynamic or 'sounded' headphones (from Beyerdynamic for example). The FiiO doesn´t fit the signature of my Sennheiser HD-448 - but the opposite happens with my Superlux HD-668B. In the end it all comes down to your preferences: if you like a dynamic, very crisp and bassy sound signature you´ll have to shun it. But if you know what you are doing and if you plan to compensate for an aggressive sound signature the FiiO E6 will be perfect for you.

Last update: 16.01.2013


  1. nice no-bullshit review, I'm am doing some research on whether to purchase a Fiio E6

  2. Hi Marlene, I have read your review( and reviews on Head fi and other sites) on the Superlux HD668B, and ordered it online.. Now I'm not an audiophile, so all the talk of crispiness, highs, lows and whatnot, makes no sense to me! All I see is, if people who know their stuff, say its good, then go for it.. :) So with that in mind, by going for a fiio e6, would a layman, like me, appreciate the way 668b will sound? Plus I have onboard soundcard on my desktop. Will connecting the e6 to the aforementioned soundcard, make the 668b sound that much different? Thanks

  3. Oh and one more thing, would I need a DAC as well?Or will the amp suffice?

    1. I can understand that you attempt to take advice from people who seem knowledgable to you. But a headphone is a very personal thing; so before buying it I really recommend listening to it because you might not like its sound. Granted, with the Superlux it doesn´t become much of an issue since it´s so cheap but it can be very aggravating if you buy an expensive headphone that someone recommended only to find out that you yourself don´t like it. The Superlux is good, no question about it. But it might not fit everyones' taste.

      Regarding the fiio e6 I assume that it´s much better suited for amplifying headphones than the output of the soundchip on your mainboard which in my experience isn´t really an output for headphone but for line-out signals. I might be wrong about that though.

      I also assume that you won´t need a DAC. The quality of the chips on your mainboard is more than good enough, the only problem I see is possible noise from the surrounding parts on the mainboard. But if you can´t hear the noise you should be OK. Why don´t you spend a bit more money and buy this one:
      It combines many positive traits of the FiiO E6 while coming with a built-in USB DAC solution. The only drawback is that it lacks high resolution capability - that doesn´t matter of course if you´re not listening to 24/96 stuff. However, the E6 and the E7 are perfectly suited for amplifying the Superlux.

  4. Thanks Marlene, I got the 668B and its awesome.. The bass is tight( understood that after listening with this headphone!) but its a bit less. Also people had mentioned that the highs were harsh and all.. I couldn't make it out though. So overall a good experience with this set. The volume is sufficiently loud enough. So does that warrant an amplifier? As per the article on NwAvGuy, its mentioned if the volume is sufficiently high enough and the sound is not distorted, its better not to go for an amp. What is your take on this?
    Thanks once again.

    1. Great that you like it! Some people mentionend harsh treble, yes. Even I occassionally have the same impression... but by that you can see that tastes with headphones differ very much and if you like it fu** all the others (including me).

      The question of an amp is not so easy. I myself would ALWAYS go for an extra amp. You don´t know the impedance of the output you´re using so you could be listening to frequency deviations colouring the sound of the Superlux. Why don´t you try out the FiiO E6? It will get rid of all impedance / power related problems the output might have. Should you be buying it at Amazon you can send it back if you don´t like it. IMO it´s worth a try.

      Just ask yourself: are you lucky with your purchase or do you want more? In case of the former let the issue rest, should the latter apply try out the FiiO.

      What I´d definitely buy though are the cushions from AKG: much more comfortable.

  5. Thanks for the reply.. and, yea, with regards to the cushions, i have already contacted a seller for the AKG K240 velour pads.. He said he will have them probably next month or so.. I'll definitely try out the Fiio E6 as you have said.. But just to be clear, the output in this case is my onboard soundcard, right? Where I connect my headphones to the line out...

    1. You´re connecting the Superlux to the line-out? Uh oh... not very good. It really is a line-out and not suited for headphones. The output impedance is way too high and the power to drive the cans is much too low. The FiiO will get rid of this and yes, you should connect it to that output (with the input level of the FiiO lowered to avoid distortions).

  6. Awesome.. Thanks for the response and I'll be ordering the E6 right away.. Now this will be truly a step up from my Koss KSC 75.. Also will it be truly beneficial to have the DAC too? Like in the earlier post where you had mentioned about the E7 USB DAC and Amp? And the front ports of the pc? Will connecting the headphones there, make a difference? Sorry for so many questions. :) .. And thanks once again..

    1. The FiiO E7 combines an Amp and a DAC in just one part. So you could have both with double the price. It´s your decision: the FiiO E7 can be used just like the E6 (analogue), it also can be used as a DAC while amplifying headphones. It all comes down to the question how much money you are willing to spend.

      How old is your mainboard? Mine is from 2008 and the audio output sucks. Noise isn´t the problem, general sound quality is. But your mainboard might be different, it might be much better. So if you don´t have very much money I´d try out the E6 and see if you´re happy with it.

      Front ports... I cannot use them. I connected them to the ASUS Xonar Essence ST and they sound audibly different. Besides, I can hear some noises of the PC through them. So I don´t use them.

      Look, I know I tend to be generalizing too much but in reality I don´t know your PC, your mainboard, your budget, how you usually hear, etc. I really might give you stupid hints.

      BTW, your Koss KSC 75 isn´t a bad headphone. It´s not balanced but that doesn´t matter. I myself was very lucky with the PortaPro for years (until I got the HD-448 of course).

  7. I know KSC 75 is a good headphone but the build quality is questionable.. Right after I bought one, the left side stopped working. Got another one and the cable was kinda wonky.. So I wanted something which is good and doesn't break itself and the wallet!

    Mine is from 2010, Asus M4A89GTD PRO.. Which I think is an OK board, but not sure of the audio capabilities of it.. Anyways I'll get an E6 with AKG velour pads and then go from there..

    1. Good decision. I´d be interested what you think, so I´d be happy if you get back and write about your impressions.

  8. i have hearing loss...i purchaed steelseries siberia v2 with usb sound card for gaming but the headphone sound is not enough loud as my hearing i want to know how much my headset will go louder if i use a fiio e6 between my usb sound card and headset...?

    1. Your Headset will be roughly 2.5 times louder (more or less 8 dB Gain). I don´t know if that´ll be enough for you.

    2. actualy i have hearing loss only in only one ear about 85%..and other is i set my window balnace 100%R and my deaf ear i feel very thin sound..
      does e6 can help me in this situation..?

    3. No, I think it won´t help. Before you start with the FiiO you might consider a hearing aid.

  9. i always go to play outside for lan event and i dont want to wear a hearing aid there...
    at the full volume of my headset i able to hear sound from my deaf side...but not much as desired i have to pay very attention to that ear side sound...
    if fiio e6 can provide some more boost to my headset full volume sound...than it can helped me...
    sorry for bad english...i am from india..

    1. It´s allright really. But I still think that the gain the FiiO would provide wouldn´t be enough. I know they´re more expensive but you could try out one of the bigger FiiOs, the FiiO E11 for example.


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