Use with a computer
Using the Fiio E17 with a computer is simple. Plug it in using a miniUSB cable and the two will start talking to each other, the E17 automatically taking over as an audio interface for the computer. No specific drivers need to be installed manually either, which makes the whole thing painless.
There are, naturally, still benefits to having a high-end soundcard rather than a USB DAC like this, though. Without a digital audio output, it's not much use if you want to occasionally connect to a surround system rather than headphones. The E17 is designed for stereo audio, not 7.1. It also has no analogue-to-digital converter (ADC), so is no good if you want to record musical instruments, or other sources, using your computer.
Sound quality and volume improvement
We have dubbed the Fiio E17 "flexible", but it's within fairly narrow constraints. Where it excels beyond the capabilities of most soundcards is in its headphone amp part. However, if the sound output from your computer sounds poor - and it's not down to your using 128kbps MP3s for your music collection - the E17 will increase audio fidelity significantly.
The headphones that benefit most from the E17's help are higher impedance sets designed for studio or home use, rather than earbuds not particularly meant for use with an amp.
The Fiio E17's effect on the sound is pretty neutral - it doesn't up-end the sound with oodles of additional warmth (the Fiio E6 adds more warmth if that is your bag) but it can seriously improve audio fidelity paired with the right set. In particular, it resolves the mid-range extremely well - smooth but well-defined in a manner that increases the soundstage size. We found it also tended to tighten-up the low-end a little, lending it greater impact and power, and helps to shave off errant top-end sharpness.
Stepping back from the minutiae of the sound, the E17 helps to smooth-out sound a little, without losing any definition or detail. It can also make headphones sound that bit more expansive. The only possible complaint we have is that the smoothed-out treble can seem like a step back with earphones that don't have enough treble presence as-is.
EQ and sound customisation
If you want to sculpt the sound output of your headphones a little more proactively, the Fiio E17 also offers some basic equalisation settings. However, they're not particularly impressive in scope.
Bass and treble can be tweaked - up or down - but you have no control over whereabouts in the frequency spectrum each does its thing. If advanced control over music playback is what you're after, you'd be better off with something like the Cowon J3 and its JetEffect 3.0 engine.
Within the same menu, gain and channel balance can also be fiddled with. There are three gain settings - 0dB, 6dB and 12dB. Higher gain settings tend to relay tunes with a little more impact, but you won't need to use them for volume alone. With such power on tap, the E17 will easily blow most eardrums at the max volume of the 0dB setting.
In the audio world, the Fiio E17 seems like a bargain. When DACs and headphone amps spiral into thousand-pound territory with ease, getting such a capable solution for around £100 seems like a small miracle. However, we do wonder how many people out there would be perfectly happy with the E7 - at half the price - or even the cheapo E6, which loses the DAC, functioning as a basic, low-power headphone amp.
However, if you have genuinely demanding headphones, the Fiio E17 has a significant impact on sound that may even surprise the nay sayers out there.
Powerful, portable and with an unmistakeably positive effect on the sound of slightly harder-to-drive headphones and the poor-quality output of some computers, the Fiio E17's worth is indisputable. It's also well-made and pretty versatile, capable of plugging into three sources at once. It is a worthwhile upgrade over the E7, though equally we suspect many of you may be happy with that device at half the price.