i jave just got my Nexus 7 rooted and running USB audio and can confirm that my MyST PortaDAC 1866 work amazing with it in USB and BT and my Fiio E17 also works. My Hippo CriCri+ and GoVibe VestAmp + had no luck however which is odd. My xDuuo XP-1 is also faulty not working with a S3, my mac, my pc and my N7.
This is an amazing rig. PortaDAC 1866 to MySt Port Amp to MyST Nail 2 V2 IEM which are amazing IEMs if anyone needs new ones. Review here: