Audioengine is primarily an active speaker manufacturer based in the US. Their Audioengine 2 and Audioengine 5 are quite popular and renowned active speakers.
Since active speakers are mostly used with PCs and laptops, Audioengine also decided to enter the DAC market. They launched the D1 initially which was quite compact and portable. However, the Audioengine D3 is even more compact and is about the size of a large USB flash drive.
There have a been a few small sized DACs released, and Audioengine has priced this one at the budget end of the range at $189. Audioengine claims that this DAC has the ability to power almost any headphone out there. Bold claims for such a small device when there are large headphone amplifiers having difficulty powering large headphones.
The drive works without any drivers and comes with absolutely no software. Volume control is done using the control on the OS. The D3 works on both Windows and Mac though there is no word on Linux compatibility.