With a pair of decent headphones, the D2+ is just a pleasure to listen to. The sound from my Denon AHC-551s was rich, warm and lovable, with a rock solid bass but more definition than I sometimes get from lesser players. The soundstage from the Denons can be crowded, but a little tweak to StereoEnhance (though not the more aggressive surround settings) seemed to help. Plugging in a pair of Sennheiser HD595s I was even more impressed.
The heavier beats and more complex production of Bat for Lashes' Daniel really came alive, and while my eardrums have been spoilt slightly through listening through the iBasso D2 headphone amp, even unamplified the HD595s delivered a gorgeous, crystal-clear, superbly balanced tone. It's certainly a versatile little devil. The stripped-back grunge of the superb Brendan O'Brian remix of Pearl Jam's Ten sounds magnificent, yet the D2+ can cope with the complex, interweaving metal of Mastodon's Crack the Skye with equal skill.
It even triumphs with the laid-back country-rock of Ryan Adams' Jacksonville City Nights and the stormy drama of Wagner's Tristan and Isolde. Some players perform brilliantly with specific musical genres but suffer when it comes to others, but the D2+ seems to cover all the bases, particularly if you're prepared to do a little fiddling with those settings.
Audio file format support is generally good, with OGG, APE and FLAC all handled on top of the usual WMA and MP3 options. However, there's no support for AAC, and I encountered a few issues with FLAC files. Tracks I've heard working perfectly well on the Samsung YP-Q1 didn't appear on the D2+ or refused to play. Apparently, a forthcoming firmware update should fix this.
The D2+ isn't a player for everyone. The design is uninspiring, the user-interface is mildly horrid and the price is still a little too high for my tastes, even given how easy it is to add capacity. For the audiophile market that embraced the original D2, however, I think that other factors, like the superb audio quality, customisable sound and SDHC slot more than compensate, as will the excellent 52 hour battery life. It's not cheap, it's not bold and it's not beautiful, but if the sound in your ears is all that matters, then the D2+ is a PMP to be reckoned with.
Not the best all-round PMP on the market, but its excellent sound quality and expandability give the D2+ an edge for audiophile users.