I am running Ubuntu 12.04 and have recently purchased a Fiio E10 DAC headphone amp to use as an external sound card. When I first plugged this in I simply had to change the output source in sound settings to the available DigiHug USB Audio device. This then worked perfectly until I unplugged the device's USB cord and plugged it back in. Now the device shows up in the output section of sound settings, but when I click it to make changes, it will not select the device, as it maintains the built-in analog output as the selection.
Nothing is muted, volumes are up, tried multiple USB cables and ports. Amp works if I send a 3.5mm cable from the analog output to the input of the device, but then I get interference so I want to use it as an external card again.
Performed the following, to no avail:
sudo add-apt-repository ppa:ubuntu-audio-dev sudo apt-get update sudo apt-get dist-upgrade
Note: I also checked alsamixer from the cli and the interface was selectable but not muted. Any help would be greatly appreciated.