As mentioned, the E09K is an updated version of the E9 headphone amp, and makes a couple of changes. Aside from the addition of RCA jacks, another small but handy tweak is that when you switch off the E09K, the docked switches off too.
Operation is straightforward, although with an E17 docked, things get a little more complicated. For example, the E17’s own volume and gain controls aren’t disabled when you dock it on the E09K, which affect the E09K’s levels. Push them both too high and it can make the level distort, so keep an eye on both levels.
The E17 has a little screen showing the current input (set it to ‘USB’ when connecting a PC) and the volume level. It also displays a setup menu, allowing you to adjust the bass, treble and gain, USB charging options, maximum volume and sleep timer. It’s a little fiddly, and the use of small volume and power buttons to navigate the menu isn’t exactly intuitive. The compact E17 also sports an SPDIF input, 3.5mm headphone jack, USB port and 3.5mm input for use as a headphone amplifier without the E09K.
We connected a Windows 7 laptop to the E09K, popped the E17 on the dock and after installing the USB driver the system was ready to rock. We plugged in a pair of Sennheiser HD598s into the E09K and ran through a variety of WAV and 320kbps MP3s on Windows Media Player and iTunes, plus lossless FLAC files in Media Monkey. Its sound quality is fabulous – sumptuously detailed, rich and open, with real punch and agility in the lower frequencies. It’ll show your headphones in a whole new light.
Starting with a batch of driving House tracks, the E09K delivers a naturally robust sound with muscular yet tightly-controlled 808 kick drums and crisp, smooth hi-hats. It’s a huge step up from our laptop’s own headphone output, with a greater dynamic range and a generally fuller sound.
Also impressive is the way it takes loud volumes in its stride. We cranked the knob up full (with the E17’s volume at a sensible level) and there were no signs of strain or hardness. It’s a really impressive little amp.
If you listen to a lot of music on headphones and care about sound quality then the E09K is the device for you. The bodywork is stylish and robust, plus its sound quality is excellent – clean and nuanced, with the power and punch to satisfy demanding high impedance cans. It’s the sort of quality you’d expect from an amp costing a lot more than £109. The only downside is that to get the most out of it, you need to pair it with the E17, which will add another £99 to the price. But given the quality of the resulting sound, it’s worth the investment.