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The unit itself is a little corker, roughly the size of a cigarette packet, weighting in at 108g and clad in a hard-wearing, shiny metal casing with cool brushed-aluminium front and back plates. iBasso seems to understand that you won't want it scratched while out on the move, so the amp comes supplied with a leather carrying pouch.
The D2 is powered by a 470mAh Lithium Polymer battery, which you can charge via the USB socket on the backplate by flicking the charge switch from ‘off' to ‘on'. iBasso claims that the battery is good for 38 hours of continuous use, and while I've been too busy plugging the thing in and out of laptops, PCs and iPods to test this properly, I don't see any reason to doubt it.
Inputs, outputs and controls are kept deliberately simple, with a 3.5mm mini-jack input and matching output on the front, along with a volume knob which doubles as an on-switch, and a ‘gain' switch that you can set up for high-impedance headphones, and down for more sensitive cans. A single, blue LED tells you that the unit is switched on.
PC setup is equally simple. Just connect the D2 up via USB and Windows recognises it as a USB DAC and installs the necessary drivers automatically, with the D2 taking over from any integrated audio solution or soundcard. I wasn't been able to test with a Mac or Linux system, but I understand from other users that it works perfectly well with the former, at least.
iPhone owners should also be warned that - like most headphone amps and speaker docks - the D2 is susceptible to noise interference. Switch your iPhone into airplane mode if you want to enjoy your music to the full.
To give the D2 a run, I first reached for my second-gen iPod touch and my trusty Samsung YP-Q1, then grabbed as many pairs of headphones as I could lay my hands on. Taking the signal from the headphone output of both players to the D2, there's a definite improvement in audio quality with just about every pair of headphones I tried. The difference is less pronounced with the Q1, which runs slightly louder than the touch and has - I suspect - better output circuits, but overall you seem to get a stronger bass, clearer mids and, generally, a livelier sound when using the D2 than when relying on the player's built-in amplification.