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:

Reference:

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:

Dynamics:

Resolution:

Stage / Ambiance:

Character:

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