While the amplifier may have done a good job of rounding out subtle tones, the E7's DAC goes further to bring out detail previously rendered inaudible by both our iPod and PC's own decoding circuitry. It's always a delight to listen to a track and finally find yourself able to discern just what's being said in that whispered dialogue over an interlude or to make out what the lyrics are to a song without needing to resort to the liner notes (or Google, if you're not the CD-buying type). The latter achievement is particularly satisfying with a group like Band of Horses, where some of the words are deliberately sung in a manner intended to be hard to decipher (because screw you, that's why).
It's worth noting that as is always the case with good quality audio equipment, you're not going to get more out of it than you put in. Although its £60 price point makes the FiiO E7 a great entry level DAC/amp combo, it's not going to make a pair of Apple earbuds sound like a set of Shure SE535 triple-driver IEMs. And even if you’re using some fairly high-end 'phones, you'll need to make sure you have good source material, too, because the FiiO E7 will highlight deficiencies in low bit-rate recordings. FLAC isn't necessarily required, but 320kbps MP3s are as compressed as you want your files to be. After all, you wouldn't watch VHS movies on a Kuro, would you?
However, if you're spending something like a hundred pounds or so on your headphones, we'd argue that £60 invested in the FiiO E7 will reap a much more noticeable improvement in audio quality than that same money spent on even pricier cans or IEMs. And while you're likely to go through a number of headphones over the course of a few years, a good DAC and amplifier is an investment that should last much longer than that.
Considering the relatively low price, the boost in audio quality afforded by the FiiO E7 is nothing short of astounding. The competition is going to have its work seriously cut out in the face of this new champion of the price performance ratio for USB-connected DAC-equipped headphone amplifiers.