It's fair to say that, for many of us, a serious, separate headphone amplifier like the iBasso D2 is the kind of luxury we think we can do without. Whereas a bargain-basement device like a Cmoy amp or the much-loved FiiO E5 is pretty much an impulse purchase, you need to be serious about your audio before you splash out £150 on a pair of headphones, let alone on an amplifier to drive them. The iBasso D2, however, leaves me pondering. Sure, I could do without it, but having heard my music with it, do I want to?
Let me explain. In the Hi-Fi world, headphone amps became popular because serious headphone aficionados felt that the built-in headphone outputs sported by most mainstream amplifiers didn't provide a signal that was clean or powerful enough to drive their favourite cans as they wanted them to be driven. A separate amplifier, tuned specifically to the needs of headphones, would provide a better result.
It was inevitable that this idea would translate to the world of PC and digital audio eventually. For one thing, the built-in amplification and output circuitry in many MP3 players doesn't have the power or the finesse to get great results from what you might call audiophile headphones, and can introduce unwelcome noise. For another, as more of us rely on PCs and notebooks as an audio source, the same can be true of the DACs and amplifiers built into our sound cards and motherboard audio chipsets. We might be busily ripping all our CDs to FLAC or Apple Lossless, but then we end up putting them through DACs, amplifiers and outputs that colour or even denigrate the signal before it even gets a chance to reach our headphones.
Cleverly, the iBasso D2 amplifier has a solution for both problems. First, it's a highly portable headphone amplifier, capable of taking the signal from a headphone socket or a line-level output and boosting it to suit the demands of even the most high-impedance stereo ‘phones. Secondly, it doubles as an outboard DAC and amplifier for PC and notebook use, using USB to stream the digital signal to Wolfson WM8740 and Texas Instruments PCM2706 DACs for processing and analogue conversion. You'll find the Wolfson chip inside high-end CD players from the likes of Kenwood, Onkyo, Rega and Cambridge Audio, so it's fair to say that you can expect a better sound than you might get from the your average integrated audio chipset.