I'm resurrecting an old thread, given that I've had success with the subject at hand -- outputting digital audio from a Tablet to an external USB DAC.
On the new Samsung Galaxy Tab Pro (10.1) I've been able to send audio via Micro USB OTG successfully to three entry level USB DACs:
1) AQ Dragonfly v1
2) Audioengine D1
3) HRT Music Streamer II
1) AQ Dragonfly v1 - I also posted in the original Dragonfly thread, but the volume level output by the Tab / DAC combo was just moderate. I could max out volume on the Tab and still be wanting for more, so this combination wouldn't be suitable for full sized cans.
That said, the SQ with my UE10s was quite good. The neutral character of these IEMs paired nicely with this bright DAC.
2) Audioengine D1 - I was able to extract much higher SPLs with this DAC / amp, maxing out the Tab volume, controlling output volume via D1. More punch isn't necessarily better, however, as this DAC is considerably muddier in clarity vs. the Dragonfly.
3) HRT Music Streamer II - Since this is a DAC-only product, I hooked it up to Magni / Mad Dogs, and this combo was solid. Good clarity, good power, drove the Mad Dogs quite nicely. The HRT registered a "48khz" signal coming in, regardless of the source file. There's a good amount of compression going on,however, as artifacts were pretty apparent.
This was a fun experiment, seeing how new source tech finally plug-n-plays with older USB audio tech.
FWIW, my LG G2 phone was able to output OTG USB audio to the Audioengine D1, but not to the Dragonfly nor the HRT Music Streamer II.
