FiiO have built a solid reputation for offering incredible bang for the buck in the portable DAC/headphone amp field. The Guangzhou City-based firm offers a wide range of desktop and portable problem solvers, among them the E6 miniature headphone amp that Brent Butterworth checked out a few months back.
The recent E17 is an updated version of the company's earlier E7, with a new chipset adding 24/92 kHz support over USB and 24/192 kHz compatibility over S/PDIF. It can also be used as part of a modular system, lending its USB DAC capabilities to the E9, an interesting little companion desktop headphone amp with a docking connector for the E17 and its predecessor, the E7 (there's also a version in FiiO's catalog called the E9i, which has an iPhone/iPod dock — the connectors aren't cross-compatible, obviously, so if you're purchasing, make sure you're getting the appropriate unit.)
Like the E7, the E17 is housed in a confidence-inspiring milled aluminum case. With its dual-color OLED display and numerous controls, it resembles nothing so much as a high-end media player, which probably makes sense since it aims to transform your pedestrian device into something better suited to your spendy headphones. And it does so pretty admirably, if at the expense of a little heft and size (though even in combination with an iPod, the total package doesn't much outweigh or outbulk something like a HiFiMan HM-801. It may not be for everybody, but it'l get you and your full-sized headphones out and about (and give you an excuse to buy a bag with appropriate pockets)
First things first — this thing sounds very good, which is to say it makes your music louder, gives you some basic tone-shaping control and basically stays out of your way. Operation is quiet, even with sensitive IEMs (we used models from Westone, Shure, and ACS), and the unit lets you make use of headphones that otherwise might not be portable.
Beyond that, the E17 offers about the deepest feature set I've yet seen in a portable DAC. Within the easy-to-navigate menus you'll find a three-position gain switch (offering 0, +6, and + 12 dB). A simple EQ is offered, with bass and treble controls, along with a balance control (and often-requested feature among listeners who don't have perfect hearing, and a welcome addition here). There's also a maximum volume limiter, and a sleep timer too. A front panel input switch lets you toggle between inputs (more in a second on that), while a hold switch keeps you from pocket-dialing some combination of features you'd rather avoid.
The user interface is quite nice (especially for a feature-packed small manufacturer product like this; many of the lower cost Chinese designs I've run across have really skimped on usability). The little OLED screen alerts you clearly to which input is live (and tells you sample rate and lock status in USB mode), while the LED indicator ring surrounding the power button glows blue while in use, red when charging, and a combo of both when doing both (as when you're connected over USB). There's even a reset switch, should you crash (I never managed to), and another to toggle the analog outputs between fixed line and variable-level preamp operation. It's all clearly enough laid out that I never had to resort to the manual.
The up and down buttons for volume control, however, just aren't to my taste; I really found myself wishing for an analog pot or rotary encoder instead. But considering how much functionality FiiO have packed into this little box at the ridiculously low price point, an omission like this is understandable.
Most interestingly, the E17 includes S/PDIF inputs via a combo jack that accepts both optical and coaxial connections (adapters for both are included in the box; you just need to supply your own cables). While USB decoding is limited to 24/96, over S/PDIF the E17 will accept incoming streams at up to 24/192 — certainly high enough for most mortals, and possibly Neil Young too. An 1/8-in minijack accepts an analog input if you want to use the E17 simply as a headphone amp, and a dock connector lets you pair the device with FiiO's E9 desktop amp (and also provides an analog line out if you want to interface with external analog audio devices but don't feel like picking up the E9; that particular mini-dock — known as the L7 — will run you 10 bucks). The E17 does a lot in a tiny package. And where it isn't quite up to snuff, the E9 can fill in the gaps.
The price for all of this performance? The E17's battery life, which is down to a claimed 15 hours, a significant cutback when compared to the E7's 80-hour lifespan. That said, unless I'm on the road, in practice I find myself charging my devices each evening or at some point during the day, and so long as I didn't leave it running I got several days of ordinary play (primarily on subway commutes) out of the combo of the E17 and my aging iPod (a 30 GB Photo model from a few generations back).
But that's all fine given the E17's dual identity as a portable companion. Enjoy it on your commute, then take it home and pair it up with the desktop E9 for serious listening sessions. The E9 is a similarly capable headphone amp (though it's an amp only — there's a USB input, but it's merely a repeater for the E17's own), with a host of options. You'll find a big, comfy volume pot on the front panel, straddled by both 1/8-inch and 1/4-inch headphone output jacks (though we're guessing this'll primarily be used with full-sized phones in any case). Around back, alongside the USB input, there's a two-position gain switch, and auxiliary input on 1/8-inch jack, a fixed-level output on stereo RCA jacks, and a variable-level preamp output on a 1/8-inch minijack. The E9 charges the E17 as it plays, so it makes a nice little "dock" for it's portable partner.
What the E9 adds on the desktop is the ability to drive current-hungry high-impedance headphones easily, and the E9/E17 pair sounds great with appropriate headphones, very much in line with the sound of my usual budget reference combo, the Musical Fidelity V-DAC II DAC and V-Can headphone amp. Output impedance is a bit high — 10 Ohms on the 1/4-inch jack, 43 Ohms on the 1/8-inch jack — but there's plenty of power on tap here (and given that the target headphones for this thing are likely to have fairly high impedances), you'll probably do OK with it's full watt of output power into a 16 Ohm load (for comparison, the E17 alone will put 250 mW into a similar load). Still, if you have full-sized headphones that don't have particularly flat impedance across the frequency spectrum, you may want to try before you buy.
The pair of Sennheiser HD-650s we tested the E9 with, however, was very well served, even in the low-gain position — everything we threw at it, from the Tor Espn Aspaas recording of Beethoven's Piano Sonata No. 32 in C minor Op. 111 (from Mirror Canon, on 24/96 FLAC); to Roxy Music's "Take a Chance With Me" from Avalon, as a 16/44.1 FLAC; to Miles Davis' "In a Silent Way/It's About That Time" on 24/96 FLAC; to the track "Alpen" from the new Oval album, Oval DNA (as a 320 kbps MP3) sounded full and rich, with plenty of volume well before the output knob hit 10 o'clock, and without unusual bumps in response. For $139, this little thing does a great job in this application.
The question is, do you really need the E9 at all if you get an E17? If you have a quality set of high-impedance phones for home listening, and prefer something else (like a set of quality IEMs) for out-and-about, you might well want to invest — it's only another $139, mind you. The E17 on its own has 1-Ohm output impedance, and plenty of horsepower for in-ears or portables, but it couldn't quite get our test HD-650s into the comfort zone (though they were plenty listenable, far more so than when driven with the iPod alone). With both devices, and a couple of pairs of nice headphones to drive for different situations, it makes sense. If you don't have difficult-to-drive cans to drive, you might be better off sticking with the E17 on its own — you won't be disappointed. The E17 does so much, and offers so much connectivity, at such an affordable price, it's something of a no-brainier if you have a need for a portable DAC/headphone amp that'll decode high-rez files.