Output: over 70mW (32ohm)
Headphone Impedance Recommendation: 16ohm – 150ohm
Frequency Response: 20Hz – 20kHz
Power Supply: 5V DC 500mA MicroUSB
Size: 23.3mm x 57.3mm x 15.3mm (main body, including clip)
Cable Length: 80cm
Battery Life: 10 hours
Build Quality and Accessories
As always the build quality is pretty good. The main unit is mostly aluminum, including the shirt clip, and the cable is fairly thick so it should be able to handle some stressing / pulling. If you are not the kind who likes to clip something to your shirt, there is a tiny hole on the clip that you can attach a lanyard cable to hand it over your neck. Accessory is minimum with just one USB cable for charging.
Navigation and Functions
On first look, E02i is pretty much like an oversized iPhone remote. The volume up/down and call button are on the front. Mic is located on the top. Shirt clip is on the back. Power and bass switches are on the left side and between them, the microUSB charging port.
The remote and mic themselves can be operated without turning on the amp section (indicated by the blue light around the call button), so you can keep using them even if you run out of battery.
Battery life is quoted at 10 hours, which is the same as FiiO own E5 / E6. Not particularly long by any mean, but still decent consider how small E02i is. I never fully drain the battery, but from daily use it seems to hold up to the spec quite well.
Gain, Hiss and EMI
E6 is about 7-8dB in gain, E5 is about 5dB, E02i on the other hand is only about 4dB. Not really a lot so low sensitivity headphone might not get very loud. The good news is the newer generation of iDevice seems to capable of outputting higher volume (which get amplified by E02i), so I don’t see any problem for E02i to work with anything below 150ohm.
Level of hiss is compatible to that of E6. Noticeable with hiss prone IEM (i.e. Shure SE530) when no music is playing but overall not an issue with most other IEM.
For something that specifically designed to use with cellphone, EMI is not an issue with E02i as it is very well shielded.
Size comparison: Left - Sansa Clip+; Right - Samsung Galaxy Ace. Sorry, don't own an iPhone, but Ace has the same dimension as the original iPhone.
RMAA measurement wise, E02i is doing quite well. First the bad news – there is a tiny roll-off in the sub-bass region. However, it is -0.5dB @ 30Hz with a 16ohm load so it should be close to unnoticeable. Otherwise E02i does measured quite well and doesn’t add anything funny to the original signal. Output impedance is measured to be a very low 0.08ohm. Output power to a 47ohm fixed load are excellent and actually doing even better with a 23.5ohm fixed load.
For the most part, I think the sound quality of E02i can be summed up as ‘E6 with remote and mic for iPhone’. The two actually sound very close in A/Bing, with the exception that E02i has a slightly warmer tone. Not a lot by any mean but it is noticeable when you listen to them side by side. While the warmer tone does reduce the background transparency by a little, it isn’t big enough to affect the actual quality of the sound. All and all, E02i and E6 are on par with each other performance wise.
Bass boost is around 5dB @ 50Hz but goes up as high as 0.5dB @ 1kHz. This is consistence to the smaller bass boost (EQ2) we have seen on E6.
RMAA via Nano 7 as source.
I guess it is not hard to see E02i as the special adapted version of E6 for the iPhone user. As far as performance goes, it is excellent for an entry level amp, much like E6. Of course it won’t replace any full size portable amp any time soon, but that is not what it is designed to do. Given how well Apple’s product usually is, E02i can served as a decent add-on but probably not a killer accessory. However, I do see a similar amp will bring much more benefit to the Android user where amp section are generally not nearly as solid as Apple products. Unfortunately E02i isn't fully Android compatible so some of the functions (volume control) will be lost if you does use it on an Android-phone, but hopefully we could see a E02A in the future from FiiO as well.