FiiO is an extremely well known audio company specializing in amplifier, DAC and recently, into DAP. While FiiO is a made in China company, but their end products definitely don't look like typical made in China products. In other words, the quality is excellent! Pure excellent for the price! FiiO is also well known for their performance to price ratio. For those who own their product(s), you'll get what I mean.
The E09K and E07K is two of their many successful products. While it does have several flaws, but overall, these two combos are just pure excitement, but that's for sure, FiiO made them to be two good brothers. They work hand-in-hand to power a high impedance headphone or any hungry headphones. The E07K is a lil brother of this rig, although he plays a huge role. The E09K is like an elder brother giving the extra "push" to the E07K. Signature wise, they match each other extremely well.
Before we get into details about sound quality, will first like to have a look at their build quality itself. Like every other FiiO products, they are nicely finished and well built. Nothing fragile. The footprint of E09K is small and does not take a lot of space on your desk. I do, however, have a minor problem on their accessories though. The power cord is just way too short. The majority of us will be using these little germs on the desktop and obviously, there will be CPU, printers etc. It would be ideal to have a longer power cord. I myself, need a shorter chair than my table to put these germs as the cord wasn't long enough for me, but that may be because my power point is slightly further than usual. I would strongly recommend FiiO to have longer cords for their E09K. USB cord is right in length and pretty standard. Both come with rubber foot. I doubt the need of using one for E07K but it's extremely useful for E09K as it sits on top of your table most of its lifetime and you want to make sure it don't get "injured" at the bottom.
A 3.5mm to 3.5mm cable is included for E07K together with two screen protector + 1 pre-applied. A pouch and silicone case is the best accessories for E07K. Comes specially handy while travelling. The screen protector is not scratch prove and I am currently using the last one that it came with. Does have some scratches already, but at least, it's not the E07K itself getting scratched.
Functionality wise, both are pretty easy to use. The tiny screen of E07K is definitely of no high resolution, but it gets its job done, greatly. I can handle it under the sun, although not extremely clear, but I find it most suitable under table light brightness. Everything can be done within just 4 buttons on the left side of E07K and "hold" switch on the right. It took me only a short while to get used to it and hey! At least you don't have to play with setting every time you wish to switch to E09K as amp or vice versa. There's just a lot of cool functions you need to explore yourself in the FiiO E07K and E09K yourself or check out FiiO website. It's too long to list in this review and I am getting way too excited about its sound quality.
First off, the FiiO E07K. The FiiO E07K have decent soundstage, but it is far from being neutral. It's more towards warm and dark sound signature. I LOVE it. I find it a good synergy for B&O H6 which is more towards thin side. The added warmth makes things sound more musical to my ears. Adding +4dB bass in the E07K gives extra "OOM" but does lose out a little if you go too far with certain headphones. Nevertheless, it's a good portable amp/DAC for starters. I find it a reasonable upgrade from my iPhone 4's internal amplifier. It makes the iPhone 4 sound lifeless, and thin. The FiiO E07K, in this combo, is a better suit for lower impedance headphone than E09K. Pretty low output impedance with plenty of power to drive most headphones to decent volume with exception of orthos. Additionally, FiiO E07K uses WM8740 DAC, which is found in many popular DACs and DAP, including FiiO's X3 and it can hit up to 92KHz/24bit for E07K.
The E09K simply takes the E07K amplifier to the next level with just one drawback; the output impedance. It should be understood that, the E09K have a 10 Ohm output impedance and that it is only suitable for headphone impedance with 80Ohm and above or any headphone with flat impedance vs frequency, but other than that, the E09K is a clear upgrade over the E07K amplifier section. Much better dynamic, a more open soundstage and it is also far more neutral and transparent. The FiiO E09K is a very powerful amplifier, and it is slightly more powerful than the already powerful E12. The E09K only take in 6.3mm headphone jack while the E07K only take 3.5mm headphone jack. You can only plug in 2 headphones at a time into this combo, otherwise, it will show error on your monitor.
After all, the FiiO E07K and E09K is an excellent desktop and portable combo. There's pre-out, line our and aux in RCA at the back of E09K which makes it very flexible for any upgrades in the future. For $200, it's a great starter rig, and it is pretty underrated here. I would have kept them if it wasn't for the need of getting a more portable solution. Highly recommended!