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FiiO Kilimanjaro 2 (E11K) Portable Headphone Amplifier


Pros: sound quality, build, output power, bass boost

Cons: Headphone/Line In ports are on the opposite side of volume control

This is a Review of FiiO E11k portable headphone amplifier. http://www.fiio.com.cn/products/index.aspx?ID=100000060416193&MenuID=105026001, available from FiiO's US distributor MICCA Store: http://www.miccastore.com/fiio-kilimanjaro-e11k-portable-headphone-amplifier-p-126.html for $59.99.

If you think the only purpose of headphone amplifier is to make a sound louder, you will be in for a big surprise to discover how much it can shape the sound and contribute to improvements in details, soundstage, etc. It is true that some headphones require more power to drive them, but I would like to focus in my review on the contributing factor of the sound improvement while using amplifier connected to a portable audio source. With E11k being my first portable headphone amplifier, I don't have too many references for comparison, though prior to E11k I have used E18 as an amplifier. Here is my impression of this latest product from FiiO.

Actually, I should start first by mentioning this is an updated version of FiiO popular budget amplifier, E11. One impressive thing about FiiO, beside constantly working on new products, they also revisit their older models to improve the design and to update the components. That's exactly what happened with E11 model where the design was updated from inside out.

Arrived in a small box (as it turned out, my review unit had an older packaging where 2nd batch will be similar to E10k), beside E11k there was also a charging usb cable, a basic 3.5mm audio cable, a pair of silicone bands, 6 pieces of rubber feet, instruction manual, and warranty card. The unit itself is very compact, measuring about 91mm x 56mm x 13.5mm, with a solid aluminum alloy body that feels very smooth in your hand and also relatively lightweight at only 92g. The shape reminds me of a drinking flask due to it's rounded toward the edges surface and volume potentiometer knob between two ramp up pieces at the top. Next to the volume, you have toggle switches for Low/High Gain and Bass boost on/off. The power turns on by turning the dial of the knob past zero where on the opposite side you will find a blue led indicator next to micro-usb charging port. On the same side as micro-usb port, you also have headphone output and aux input (3.5mm ports) located symmetrically on each side of micro-usb port.

I do have to mention it was a bit awkward to see Headphone and Line In ports on the opposite side of the volume knob, and perhaps for some this will affect a connection of audio cables and the logistics of placement to have access to volume control. At the same time, it really doesn't require to use two fingers to turn the volume knob, and I was able to use just my thumb. As a matter of fact, I tried my X5 with HS6 kit (designed for a larger E12 amp) using a single rubber band to hold down E11k, and found it to be working quite well. Also, want to mention that I really like the audio cable from HS6 kit, something you can get separately as L16 short cable from FiiO. Furthermore, I know some will notice a shape of E11k to be not perfectly flat, but next to a flat surface of a DAP (even using X5 without a silicone skin for the purpose of HS6 kit) - it felt sturdy without wobbling. For an extra security, you can use included rubber feet that just stick on to the body of E11k. Personally, I think E11k will make a PERFECT pair up companion for the upcoming X1 DAP.

Don't let the small size of this amplifier fool you since it actually hosts a hefty 1400 mAh battery (non replaceable) which can provide over 16 hours of continuous play. I have been using E11k in a low gain setting for almost two weeks now and have a feeling it can probably stretch pass that limit. And even if you run out of juice, you can continue using amplifier while charging it up. Gain toggle provides a decent boost in volume to assist in driving demanding headphones, and the extra power actually helped to bring up more details even in less power hungry IEMs. I also found Bass boost to be surgically clean, where flipping that toggle provided a more controlled enhancement of sub-bass quantity and some mid-bass punch without spilling into mids and muddying the rest of the spectrum. In contrast, E18 bass boost wasn't as tight, and bleeded a bit into lower mids.

So how good does this amp sounds and how much improvement are you going to get over your built-in amp? There is no simple short answer to this question, and that is a beauty of amplifiers where it will depend on it's pair up with your source. One thing I found for sure: the sound will always improve, but to what degree you can never predict so it was a journey to try different hardware sources as well as using connection to Line Out (LO) or Headphone Out (HO) to find a better combination. Typically, you want to drive your external amp from LO, but it never hurts to experiment. At the current moment my two main DAP sources are X5 and AP100, and for example I found E11k connected to HO pairs up better with AP100 rather than X5. But once I switched to using LO port, I found a combo of X5 + E11k to show more improvement over AP100 + E11k. As a matter of fact, while I prefer AP100 built in amplifier over X5 built in amplifier (by comparison of direct HO connection and while AP100 is in 24b/192k oversampling mode), X5 actually sounds much better with E11k from LO. Also, comparing the sound between X5 with direct headphone connection vs LO with E11k, I found the sound to get wider and deeper (soundstage), overall tighter, brighter with more details while still being smooth, and a significant bass improvement (deeper and punchier). A performance of X5 paired up with E18 as amplifier connected to LO was inferior in sound quality to E11k where E18 colored the sound to be darker, less transparent, and with less details in comparison to E11k.

Overall, I found that amplifier adds another variable to a complicated equation of sound where you already have an array of file formats, different hardware sound sources, and various headphones. There could be numerous combinations and it's a never ending journey. One thing I discovered for sure, if you are serious about sound quality - amplifier is a must have addition to any setup. With E11k being a very portable and a very capable amp, I found it to provide a noticeable improvement to X5 DAP when comparing direct HO connection vs LO w/E11k. It has just a perfect balance of clarity and transparency with a touch of warmth without adding too much color or distortion when paired up with a capable DAP that has Line Out. For use with smartphones or supported tablets, I would still recommend E18 which goes straight from digital domain to internal DAC/amp of E18. For everything else, E11k is an excellent portable amplifier on a budget!

Here are the pictures.


























Fiio is a Chinese maker of audio equipment that has become well known for offering good gear at highly competitive prices.   With a lineup of competent, if not highly compelling, DAPs, amplifiers, and DACs, Fiio has generally been incredibly fast in reacting to audiophile market trends.  The previous E11 was a budget portable amplifier aimed primarily at winning the hearts (and ears) of IEM/ portable headphone users.  It turned out to be quite successful, and received some serious praise from many members of the audio community for offering a solid SQ in a small package (size and budget-wise).  However, the E11 did leave a few things to be desired, including a better housing, sharper design, and a refined SQ.   


Before I go any further, I would like to offer a big thank you to Sunny at Fiio for sending a review unit for the purposes of writing this review.  As always, I am neither an affiliate nor an employee of Fiio, and all photos are taken/ owned by me.



Weight: 92 grams

Audio Input: 3.5 mm Jack


Drive Ability: 16-150 Ohms

Output Power: 270 mW (32 Ω/THD+N1%)

                        450 mW (16 Ω/THD+N1%)                                                  

THD: 0.004% (1 kHz)

Frequency Response: 20-20 kHz

Input Sensitivity: 2.4 V (GAIN=L)

                           0.8 V (GAIN=H)                                                                              

Gain: -3.8 dB (GAIN=L)

         11.7 dB (GAIN=H)




The E11K comes in a no frills package.  The thin laminated paper cardboard box opens to reveal a pullout tray covered with faux crocodile skin.  It is a rather odd design choice, but Fiio products aren’t about awe-inspiring unboxing experiences anyways.  The expected accessories can be found, including a few rubber bands, a 3.5mm to 3.5mm cable, and 6 3M-rubber feet.  It is a bit of a shame to see the 30-pin to 3.5 mm cable go, but I guess that that can largely be attributed to Apple’s move to adopt the all-digital Lightning cable.




Fiio has definitely stepped up its game in terms of build quality.  The new E11K now sports the same black, brushed aluminum exterior that can be found on the Fiio X3 DAP, E12 Mont Blanc, etc. Needless to say, it looks pretty darned good. The volume control feels solid, and is protected by a conical leading edge on both sides (Astell & Kern anybody?).  On the same side as the volume control are the gain and bass boost controls.   Both controls are flip switches made out of plastic, and do jut out a fair bit from the player.  Take extra care as you remove the rubber bands from your E11K/DAP setup, as simply sliding it off the player will cause the rubber band to slide onto the two plastic controls (and possibly snap the plastic bits).



On the other side of the amp are the Micro USB charging, line out, and headphone out ports.  Why Fiio chose to have the headphone out on the opposite side of the volume control is beyond me.   The ergonomics of this setup are naturally rather awkward and even a little troublesome at times.   I had to reach deep into my pocket (thankfully, not for my wallet) to get to the volume control.



The Fiio E11K has juice.  For a 60 dollar amp, it can power IEMs wonderfully and some headphones quite well.  Turning the E11K on and off, I couldn’t help but to notice the rather significant pop.  To mitigate possible damage, I generally preferred to unplug my earphones first in both of the above situations.  This is troublesome, especially considering that this amp is most often used in portable setups.  I should really just be able to just flick toggle on and off with relative ease and not have to worry about possible hardware damage.


The sound is relatively pleasant, and leans slightly towards the warmer side of things.  The amp is relatively conventional, and doesn’t make any unexpected changes or additions to SQ (not that an amp should really be doing the former in my opinion).  Soundstage is moderately sized, but I wished that it was slightly larger.   Imaging, like the soundstage, is pretty good as well.  However, do not expect to be able to pinpoint every detail or the location of the various instruments.  It is very important to note that this amplifier is only sixty dollars though!  For sixty bucks, it’s doing a great job at simply fulfilling its job scope –amplifying sound.


Bass boost is surprisingly unobtrusive, and adds bottom end fullness without causing significant bleed into the mids.  In fact, some might be disappointed that this isn’t producing a huge bass bump.  I found this to be a great thing for IEMs though.  More often than not, IEMs need just a slight alteration of SQ and not massive overhaul courtesy of the amplifier.  For my ATH-IM02s, the Fiio E11K gave just a small push that helped to make the earphones more musical (by enhancing low frequency performance).



Fiio has done a great job in my opinion.  While users who have listened to more expensive setups will probably not be wowed by the E11K, it’s hard not to be impressed by the good SQ at the extremely reasonable price point.  For portable use, I feel the E11Ks do a wonderful job, and those who have not been amping their earphones/headphones or are considering a more portable setup should definitely look into this mean, lean, amping machine.


Pros: Audio Quality, Amazing Build,Looks,Battery

Cons: Pops up while starting, A tiny tiny bit of reduction in soundstage while enabling Bass (Varies from player to player)







First of all I'm not a basshead & I have 2 earphones & 1 headphone. This review is based on those



Things I used :


Tablet & Computer for source (Both having average/below average DAC I presume)

Headphones : Sennheiser HD 449,Sennheiser CX 180 Street II & Sony MDR XB70-AP


Review :


Build : One word,pretty amazing. It has lightweight brushed metal covered body without feeling

cheap,& it's sleek & sturdy. Every knob is carefully built & easy to access,especially the volume knob is

very well done. Rating : 5/5


Accessories :
A 3.5mm male to male almost 3 inch cable,
button-like rubber feet,USB charging cable,
Silicone bands (x2),
Owner's Manual,
Warranty Card. Rating : 5/5


Performance :


Battery : It has 1400 mAH Li-Ion battery and it lasts really really long. I've watched a Full movie with

3-4 hours of music playing & it's still showing that the battery is full. So good work there Fiio. Rating :



Sound :


Treble : Good emphasis on treble without making it too sparkly or fatiguing. Well detailed & well

spaced nothing to complain. Rating : 4.5/5


Midrange : Well detailed,almost true to the source. Good separation between midrange & other

treble-based instruments. Rating : 4.5/5


Bass : Well here comes the tricky part. What I've found,after few hours of listening from my

tablet that Turning the Bass switch on in my E11K (which has a discrete hardware accelerated bass

circuit) has a different effect on the music than Software accelerated ( Graphic EQs,Bass Boost

through Software) boosting,which comes with media players. Where the software accelerated Bass

boost/EQ is somewhat uncontrolled,noisy & sometimes bloats out the overall frequency range (if not

used properly),the discrete bass circuit of Fiio E11k doesn't do that... It adds a fine touch of depth in

the music without influencing any other frequencies. In that sense I would like to rate it the highest. But

there's a slight problem. I've noticed while playing from Tablet, turning the Bass ON reduces the

soundstage somewhat (a very little bit) & THAT also varies upon which player I'm running the musics

on. e.g the Stock music player performed best than High end players like Jet Audio/Neutron Player

etc. Before buying the amp I always thought my Tablet gave better sound in headphones than my PC.

But after attaching E11K with my Sennheiser HD 449 to my PC. WHOA. A whole new story. It

simply outperforms my tablet in every aspect. I used DFX to enhance SQ while playing games & was

satisfied with it. But after I attached E11k I found that which details were somewhat "PRESENT"

before are much "EVIDENT" now.  To be precise,E11k blows DFX out in every aspect.

It gives proper juice to your headphone & sounds amazing where DFX  now feels inferior.

I don't have to listen to it to find out the detail... It's already there.

And the constriction of soundstage I referred before in my tablet is almost negligible (or almost

absent) in the PC. So to sum it up,It's the DAC that has lion's share in the SQ. Even though Amps

chisel it out,it cannot change what's coming to it as a feed. So in Bass I'll rate it 4.5/5


Performance Variation : Although E11k increased the SQ of all 3 headphones/Earphones of mine. I

got most out of it while using with my Overhead HD449. I think the CX180s & XB70s were well fed

from my tablet only... Using E11k makes it slightly better though,but it doesn't make a difference as it

makes with HD449s

Soundstage : Satisfied with it. Almost True to the source. Good instrument separation.


Price : Around Rs. 3.7k +. I haven't used any amp before so can't comment on this section :P


Overall : A highly recommended product,if you think you need more juice for your headphone. More

suitable for Overheads. It's highly recommended to use it with a good DAC. I'm hoping to buy one in the future.Thank you for reading. I'll give it  4.5 stars out of 5

FiiO Kilimanjaro 2 (E11K) Portable Headphone Amplifier

FeatureFiiO E11K
TitleFiiO Kilimanjaro 2 (E11K) Portable Headphone Amplifier
Item Height2.2 inches
Item Length3.59 inches
Item Weight0.2 pounds
Item Width0.51 inches
Package Height1.02 inches
Package Length5.2 inches
Package Weight0.35 pounds
Package Width5.12 inches
Model Name/TypeMPNEAN/UPC
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