Was terrific surprised when even my Creative speakers at the office lifted.
Run with Sennheiser Momentum normally but now I have racked my HD555 also, and this little gadget is fantastic, again, I hear new things and the bass is deep and the voices are clear but nothing is strained.
It works with your phone is not wrong either.
Sounds amazing, no noise. Has very low latency during playback. Very nice with physical volume control on the device. Supported in both Windows, Mac and Linux. Nice price in relation to quality.
What I have to gripe it is that it gets very hot. Not recommended to leave it covered under a pillow or blanket on the couch unattended! Another weakness is that in Linux so only supported 24 bit playback (USB 1 mode) and 32bit float (USB 2 mode). It does not support physical 16-bit playback. That means that if you listen to 16-bit audio (the most common), this must be converted in software first. This causes unnecessary level processing computer. Obviously no problem for modern desktop / laptop computers. But if you, for example. use it with a Raspberry Pi or mobile phone / tablet, so this could be a problem for battery life and reduced processing power.
Got to try this by HIFI club. Unfortunately, I heard no difference whatsoever on any of my headphones as I listened to my macbook pro retina. Apparently circuits from Apple already so good compared to many PC computers. Had to return the product.