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INTRODUCTION
When I first came to Head-Fi I was naturally curious about portable amps. When I got my first one (the old E7) I was blown away – the increase in clarity, details, soundstage! Then over time, as I read more, experimented more, and (more importantly) tested more, I can to realise that those benefits I was sure I heard, had mostly come about by simply turning the volume up. And with the portable amps I was using, I wasn’t volume matching when comparing. Once I actually started comparing objectively, most of the time those differences disappeared. Sure – there are times when you absolutely need an amp – like with the 320 ohm VE Zens, or if I want to drive my HD600s portable, and there isn’t enough volume. But for a long time with my portable listening, I stopped carrying a portable amp.
Then around Sept/Oct 2014, I worked with Fiio to set up a “Down Under tour” for their new X1 DAP, and as a bonus they also threw in their E11K amp. At the completion of the tour, I offered to buy both units from Fiio (and yes – I paid real money for them), and the last 12 months has given me a whole new perspective on portable amping, why you might want to use one, and why the budget prices E11K (A3) portable amp from Fiio should be considered.
ABOUT FIIO
By now, most Head-Fi members should know about the Fiio Electronics Company. If you don’t, here’s a very short summary.
Fiio was first founded in 2007. Their first offerings were some extremely low cost portable amplifiers – which were sometimes critiqued by some seasoned Head-Fiers as being low budget “toys”. But Fiio has spent a lot of time with the community here, and continued to listen to their potential buyers, adopt our ideas, and grow their product range. Today, their range includes DAPs, portable amps, portable dac/amps, desktop dac/amps, earphones, cables and other accessories.
Fiio’s products have followed a very simple formula since 2007 – affordable, stylish, well built, functional, measuring well, and most importantly sounding good.
DISCLAIMER
The E11K (A3) portable amplifier that I’m reviewing today was purchased by me (direct from Fiio) at the end of the Australasian tour I organised. I have no obligation to write this review, I am not affiliated to Fiio in any way, and this is my honest opinion of the E11K (A3).
PREAMBLE - 'ABOUT ME'.
(This is to give any readers a baseline for interpreting the review).
I'm a 48 year old music lover. I don't say audiophile – I just love my music. Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current set-up. I vary my listening from portables (Fiio X5ii, X3ii, LP5 and iPhone 5S) to my desk-top's set-up (PC > USB > iFi iDSD). I also use a portable set-up at work – either X5ii/X3ii > HP, or PC > E17K > HP. My main full sized headphones at the time of writing are the Beyer T1, Sennheiser HD600, and AKG K553. Most of my portable listening is done with IEMs, and lately it has mainly been with the Dunu DN-2000J, Jays q-Jays and Alclair Curve2. A full list of the gear I have owned (past and present is listed in my Head-Fi profile).
I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock. I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock. I am particularly fond of female vocals. I generally tend toward cans that are relatively neutral/balanced, but I do have a fondness for clarity, and suspect I might have slight ‘treble-head’ preferences. I am not treble sensitive (at all), and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and DT880.
I have extensively tested myself (abx) and I find aac256 or higher to be completely transparent. I do use exclusively redbook 16/44.1 if space is not an issue. All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line).
I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, have never heard a difference with different cables, and would rather test myself blind on perceived differences. I am not a ‘golden eared listener’. I suffer from mild tinnitus, and at 48, my hearing is less than perfect.
For the actual listening part of this review I used the E11K (A3) mainly with my X3ii or X1 DAP, and a little bit with the iPhone 5S. Observations about the E11k (A3) are taken from the past year I’ve owned it. This is a purely subjective review - my gear, my ears, and my experience. Please take it all with a grain of salt - especially if it does not match your own experience.
FURTHER NOTES
- Although Fiio are in the process of rebranding/renaming their portable amp line from E series to A series, from this point I’m going it simply call it the E11K. It’s just easier.
- Volume matching was done with a calibrated SPL meter and test tones (1 kHz) when required for comparison.
- Frequency response and distortion measurements were taken using a relatively cheap Startech USB soundcard (which measures pretty well – 0.012% THD and 0.024% THD+N – which was consistent at 300 Hz, 1 kHz and 6 kHz @ -3 dB volume as suggested by ARTA using loopback). I combined this with a licensed copy of the ARTA measuring suite. The soundcard has a calibration adjustment applied – so that it measures dead flat from 20 Hz to 20 kHz.
WHAT I LOOK FOR (NOW) IN A PORTABLE AMP
I thought I’d list (before I start with the review) what I would now look for in a portable amp. This is useful to remember when looking at my reasoning for scoring later in the review.
- Genuine portability
- Good battery life
- Clean, neutral signature
- Easy to use
- Low output impedance
- Reasonable output power – should be able to drive IEMs and earphones up to 300 ohms
- Good gain control
- Value for money
PORTABLE AMPS I’VE OWNED IN THE PAST
- Fiio E7, E11, GoVibe Porta Tube, Headstage Arrow 12HE 4G, Beyerdynamic A200p
- Current portable amps E11K, E17K, VE Runabout
THE REVIEW
PACKAGING AND ACCESSORIES
The E11K arrived in Fiio’s retail packaging – a white, red and black box measuring 130 x 130 x 25mm. The front had a picture of the E11K, and the rear has some specs and other information in English and Chinese.
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Retail box - front | Retail box - rear | Retail box - profile |
Opening the outer retail box reveals an inner box with a foam cut-out (securely holding the E11K), and a secondary box for the accessories. The accessories include:
- 6 stick-on feet
- 1 x 3.5-3.5 mm cable (Fiio’s L8 mini to mini)
- 2 rubber stacking bands
- A USB to mini-USB recharging cable
- Warranty and instructions
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Inside the box E11K + accessory box | Accessories | Cables - interconnect and USB charging |
The entire package is practical, covering everything you initially need for the E11K. Materials are all good quality. If there was one thing I’d change it would be ditching the silicone feet (they slide around on the body) and instead including one of their silicone stacking pads.
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Manual and warranty envelope | Stacking bands | The Fiio E11K |
TECHNICAL SPECIFICATIONS
The table below lists most of the relevant specifications for the E11K.
Output Impedance H/O
| <0.2 ohm
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Recommended Headphone Impedance Range
| 16-150 ohms
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Max Output Power @ 16 ohm
| 450 mW
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Max Output Power @ 32 ohm
| 270 mW
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SNR
| >108 dB
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THD
| 0.004% (1 kHz)
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Frequency Response
| 20 Hz-20 kHz
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Gain
| -3.8 dB (L) / 11.7 dB (H)
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Channel Imbalance
| <0.3 dB
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Max Output Current
| 92.6 mA
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Max Output Voltage
| 8.67 Vp-p
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Dimensions
| 91 x 56 x 13mm
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Outer Material
| Brushed Aluminium
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Headphone Out
| 3.5 mm
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Weight
| 92g
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Battery Capacity / Life
| 1400 mAh / ~ 16 hours
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Recharge Time
| 4 hours
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BUILD / DESIGN
The E11K is rectangular shaped with slightly bevelled edges, and a slightly curved top side and under side. The main body is a solid machined block of aluminium. At one end is the Alps potentiometer – nicely nestled between two raised protective arms (so it’s more difficult to accidentally bump the pot), the high/low gain switch, and the on/off bass boost.
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Front/top panel | Gain switch and better view of edge bevelling | Rear/bottom panel - ports |
At the other end is the 3.5mm headphone out jack – still nice and firm after a year’s use, a blue LED (solid blue when on, flashing blue when charging), a micro USB charging port, and the line-in 3.5mm port. Overall the external build is really solid, and even after a year my unit has very few scratches or bumps. The curved surface feels good in the hand, but it is the one design error I think Fiio made with this amp. It’s simply not that well suited for stacking (and that is what a portable amp will be mainly used for after all). If you’re using other Fiio gear with it, then their stacking kits and silicone pads really help – but the curved surface wasn’t one of Fiio’s smartest choices in this case.
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Underside | In use LED light | E11K charging - LED slowly pulses |
Opening the unit up, it’s easy to see the curved one piece body, and also how compact and tidy the layout is. One thing I also noticed was that the underside is fitted with a shroud. I guess this has two possible uses – as a guard against accidental static flashes from the board – but maybe also as an EMI shield. Compared with the older E11 (which I used to own), I have had no problems with EMI (and with the old E11 this could be an issue).
Some may find it a bit strange that the ports are at the opposite end to the volume pot – but I actually (over time) have found it quite natural. The good thing about this configuration is that the volume pot, bass boost and gain switches are very easy to get at (no cables getting in the way).
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Opening the E11K | Note the curved aluminium body | Battery and caps |
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Ports exposed | Underside has antistatic pad/shielding | Close up of the caps |
HEAT AND POWER
So far I’ve noticed no heat build-up at all with the E11K. Even after a couple of hours (driving my HD600s), it’s still cool to touch.
For output power the E11K uses the OPA1642 for preamp and the AD8397 as its power amplifier. Fiio rates the target headphone impedance as 16-150 ohm, and I think that maybe a lot of people see this and automatically assume this little unit can’t drive a headphone like the HD600 (300 ohm properly).
But as I do the final edit of this review, I’m sitting with the X3ii feeding the E11K, then into my HD600’s. Volume on the pot is around 3/9 (low gain), and I’m getting a very comfortable 65-75 dB with minimal effort. This is my usual listening level so I’m pretty content. Taking the HD600 off my head, and cranking to maximum volume gives me 90 dB peaks. High gain would add another 15 dB to take that to 105 dB – more than you’d ever need. And at no stage do the HD600 feel under driven.
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E11K with HD600, VE Zen and DN-2000J | E11K with DN2000J | E11K and X1 (with stacking kit) |
Note that although this series of photos shows E11K with Fiio X1, the X3iiw as actually used in testing
With a variety of headphones / earphones at my disposal, the test track “Sultans of Swing” by Dire Straits, and X3ii feeding E11K via line-out at low gain – these are the approx. volume settings to get to a comfortable listening level (for me) at around 70-75 dB on low gain:
- HD600 (300 ohm, 97 dB SPL) = ~ 3-3.5/9
- VE Zen earbuds (320 ohm, 106 dB SPL) = ~ 2.5-3/9
- Trinity Delta IEMs (16 ohm, 110 dB SPL) = ~ 2/9
- Dunu Titan1 IEMs (16 ohm, 90 dB SPL) = 2-2.5/9
- AKG K553 Pro (32 ohm, 114 dB SPL) = 2.5-3/9
- Dunu DN-2000J (8 ohm, 102 dB SPL) = 2/9
And for giggles because I can
- Beyerdynamic T1 (600 ohm, 102 dB SPL = ~ 4/9 (Not recommended though – sounds a little thin)
So you can see that the E11K has a heap of power on tap – far more than its recommended 16-150 ohm headphone range belies. Clearly Fiio are being safe with their recommendations. Even switching to my lower output iPhone 5S (at full volume emulating a line-out) into the E11K, and again pairing the HD600s, the E11K only needed a slight bump to around 4/p on the pot.
FEATURES / USEABILITY
The E11K couldn’t be much simpler to learn to use. Simply plug your source into one socket, headphones into the other, press play on the source, and adjust the volume on the pot of the E11K to suit. The E11K has a really low output impedance (<0.2 ohm) so it should suit even the most sensitive earphones.
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Using the bands to stack my iPhone 5S | iPhone 5S connected | E11K with X1 left and X3ii right |
It does come with a bass boost (on/off) which I’ve measured as lifting the entire volume by about 1 dB, then lifting the bass between about 30-200 Hz with the main peak at 60-80 Hz – around 3.5 additional dB. It is noticeable but subtle (which I rather like). There is also a gain switch which raises the overall volume by ~ 15.5 dB. The thing I like about this is that it a decent change in gain, and actually makes a difference – rather than just being put there as an afterthought. Unsurprisingly, I really don’t use the gain toggle at all – unless it’s a low powered source, and a hard to drive load. Nice to know it is there though.
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Fiios stacker kit | X1 and E11K stacked | X1 with E11K stacked |
Another feature which has been added from the original E11 is that this time you can charge the E11K and still listen at the same time. Nice for those moments when battery is almost gone, you’re close to a power-point, and you still want to be listening. The other thing I really like about the E11K is simply having a proper pot to use. It’s really nice being able to get to an ideal listening level with a very quick tweak of your fingers. I’ve noticed virtually no imbalance either – even getting to the bottom of the pot.
BATTERY LIFE
Fiio rates the play time on a full charge at around 16 hours, recharge at around 4 hours, and for my use I’d suggest that time is pretty accurate. What I really like about the E11K though – and probably the reason I use both it and the E17K so often now – is that using it with the Fiio X1 or X3ii line-out extends battery life on both Fiios by at least 5 or so hours. So if I was going to be on a long haul, or somewhere I simply needed extra life with my DAP, one of the two amps always comes with me.
SONICS AND PERFORMANCE
I’m going to preface this section with a little critique I received a while ago (by PM), and my answer to it – so that you can understand why I don’t comment on some things, and why I do comment on others. I was told my review on another amp was poor because I didn’t include sections on bass, mid-range, treble, sound-stage, imaging etc – yet referred to an amp as warm, full, or lean.
Now I can understand the reference to warm / full / lean – as they are very subjective terms, and whilst I’d like to avoid their use, they are invaluable to convey true meaning. Comparing my NFB-12 to the Aune X1S for example – the Audio-gd does sound richer and warmer. It’s the nature of the DAC which is used.
But I choose not to comment on bass, mids, treble, and most definitely not sound-stage – simply because when we are talking about an amp – they shouldn’t be discussed. An amp’s job is to amplify the signal with as low distortion as possible, and output as linear signal as possible. If it is doing its job properly, there is no effect on bass, mids, or treble. And IME an amp does not affect soundstage (unless there is DSP or crossfeed in play) – that is solely the realm of the transducers and the actual recording.
So we have that out of the way how does the E11K perform sonically?
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Channel matching within 03 dB | Normal signal (low), bass boost, and high gain | Close up of bass boost |
The first thing I did was to check the linearity of the E11K, check its bass boost and its gain. To do this I used a calibrated sound card (calibrated to measure completely flat), ARTA and a loopback. In the low gain and high gain frequency tests the E11K measured flat – amazingly flat. So what you are getting is an amazingly neutral amplification not adding or taking away anything. Channel balance throughout was also very good - approx than 0.3dB and for me that meant completely unnoticeable. The graph above is a close-up.
Next up was distortion measurements. My USB soundcard measures (on loopback) THD at 0.010%-0.013% and THD+N at 0.020%-0.032% at pretty much -100 dB (this was with separate readings at 300 Hz, 1 kHz and 6 kHz). When I added the E11K – I got exactly the same measurements with it in loopback – so the E11K is measuring lower than my USB sound card can measure. It also means that the distortion and harmonic distortion are both inaudible. Fiio states measured THD at 0.004% on their lab equipment, and I have no reason at all to doubt this figure.
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THD and THD+N @ 300 Hz | THD and THD+N @ 1 kHz | THD and THD+N @ 6 kHz |
The last thing I measured was IMD, and again this was below the threshold of audibility, and again the E11K was measuring below the actual thresh-hold of the USB sound card. So what does this tell us? Simply that the E11K supplies very linear, and very clean output. Purely subjectively, it sounds very neutral – no added warmth or brightness I can discern.
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IMD @ 300 Hz | IMD @ 1 kHz | IMD @ 6 kHz |
COMPARISONS
Because I don’t have a lot of other amplifiers at my disposal, I simply used what I had available – the VE Runabout, and the Fiio E17K.
E11K (USD $60) vs VE Runabout (USD $100)
The VE runabout is VE’s first portable amplifier (from the same company that brought us the excellent Zen earbuds). It is battery powered (9v battery), and at 235g and dimensions of 110x70x25mm, it is quite literally 3 times the size of the E11K. It also measures below the distortion floor of my sound-card, and measures completely flat in frequency response. It has a gain switch (only ~ +4-5 dB), and no bass boost. Battery life is incredible – it seems to go forever (I haven’t measured it yet – but will do so when I review it). According to VE it will put 150 mW into 32 ohms, which actually puts it behind the E11K on output power – but again it has driven my HD600 with absolutely no issues. In a volume matched blind-test, I can’t tell the E11K and Runabout apart – both sound excellent – clean and clear. But in a head-to-head comparison, the little Fiio beats it handily on size, portability, weight, form factor, features, and value.
E11K (USD $60) vs E17K (USD $130)
The E17K is a DAC/amp. It has an inbuilt battery (15 hour rating) and digital volume control instead of analog. At 110g and 104x62x13mm, it is marginally larger than the E11K – but the difference is mainly in length. It has 3 levels of gain 0dB, 6dB and 12dB, and has a tone toggle (-10 to +10 bass, and same on the treble). Again it measures below the distortion floor of my sound-card, and measures flat in frequency. Its output is 200mw into 32 ohms (a little less than the E11K) and again has no issues driving my 300 ohm Sennheiser HD600s. Again in a volume matched blind-test, I would have difficulty picking the E11K from E17K. The E17K does however have a very good DAC, tone controls, balance, and other inputs and outputs, and is incredible value at $130.
If I only needed an amplifier, and had no need of the other features the E17K provides, the choice of the E11K is an easy one to make. However, if you like having the additional features, and have use for the dac function, then the E17K may represent better value.
E11K VALUE & CONCLUSION
I’ve now had the E11K for a year, and although I didn’t use the unit a lot in my early days with it, over the last 6 months, I have come to use it more and more. If you are using Fiio DAPs like the X1 or X3ii, I can thoroughly recommend the stacking kit too.
The E11K brings very good size, weight, power, and sonics together in an extremely budget friendly package. In fact, I cannot think of a better amp to recommend to someone just starting out in audio, and I think ultimately even seasoned audio lovers may really like what Fiio has brought to the table with this mini dynamo. In fact for a beginning audiophile, one of the best value for money combos you could get would be an X1 + E11K + stacker kit IMO.
Going back to my original list – I can say it has ticked every one of my boxes my boxes for portability, ease of use, output power, battery life, sonics, impedance, and gain. If there were two minor things I would like to see changed it would be to see a two stage gain (maybe make the first at around -6dB, then at +3 dB and +12 dB. This would give more usable play on the pot (fine tuning). And also I’d like to see the form factor return to a flat body– so that it is easier to stack (although with Fiio’s stacking kits this is less of a problem).
All in all, I would recommend the E11K to both audio starters and the more experienced without question. For what it delivers, it is incredible value for money.
