If you consider yourself an audiophile, and have a large collection of digital music, you've probably spent a large chunk of change on a pair of headphones to plug into your PC or Mac. But here's the kicker: those headphones are only as good as the soundcard installed on your computer. And if you have a crummy soundcard, your music will sound lacklustre regardless of the luxury cans you slap over your ears.
But help is at hand with the external DAC, or Digital-Analogue Converter, which you plug into your machine via the USB port to bypass the built-in soundcard and reprocess the music at the source. Some models will also include a headphone amplifier to boost the volume. You won't need particularly sensitive hearing to notice an immediate improvement in sound quality, but from then on, it's nigh-impossible to continue listening to music on your computer without a DAC.
With that in mind, the market for DACs and headphone amplifiers has exploded in recent years. Niche brands have popped up all over the place, built for a variety of purposes. You can buy a DAC on its own, or a headphone amplifier by itself, or you can kill two birds and have both options combined in one unit. So the big question is, which model is right for you?
The Fiio Alpen-E17 is the undisputed king of portable DACs, at least as far as the experts at Head-fi are concerned: "Have tried many headphone DAC/Amps in the £50 - 200 range and nothing comes close to the resolving, enjoyable nature of this bit of kit." A great entry-point for first-time users, it has a reassuring build quality and is solid value for the money. Link.
One consequence of the ODAC is that, according to a reviewer at Head-fi, "bad recordings now sound terrible and good recordings sound terrific". Can be bought as a standalone, USB-powered DAC unit, or combined with a headphone amp that needs to be powered off the mains. Either way, you're onto a winner. Link.
Named after the burning rainbow bridge of Norse legend, spanning the worlds of Gods and men, the Schiit Bifrost is an imposing piece of hardware with a divine purpose: to lift you up to audio heaven. This DAC is housed in an imposing slab of aluminium, with modular components for easy upgrading, and can be paired up with a range of amps also designed by Schiit. Link.
With its old-school vacuum tube amplifiers, the WA7 is an expensive proposition. But to some folks, it's entirely worth it. "So gorgeous even the most unsupportive of audiophile wives will allow it in without asking too many questions," says one chap at Head-fi. "Sounds as good as it looks, compact." Link.
Housed in a rugged anodised aluminium shell, the Audioengine D1 accepts signals through both a USB and optical connection. The latter has the benefit of accepting content of up to 192kHz/24-bit, rather than the USB connection's 92kHz/24-bit limitation. This is most useful, for example, when cleaning up streaming audio via Apple TV or AirPlay. Link.
These five DACs are great examples, but we've only just scratched the surface. It may take a fair bit of research to pair up the right unit with the right headphones and your budget, and it certainly helps to follow the recommendations of the folks at Head-fi for detailed scrutiny of each model. But the reward is worth it; elevating the enjoyment of your music collection for many years to come.