I've ran into the exact same problem. I am currently using pulseaudio volume control (pavucontrol) as a workaround.
Install PulseAudio Volume Control from terminal: (Ctrl+Alt+T)
sudo apt-get install pavucontrol
Once it's installed, run the program:
pavucontrol
You will find the emu sound card listed as an output device. If not, try reconnecting the device.
Set the profile of the sound devices you don't use to off in the configuration tab and check that the E-mu card is set to Analogue Stereo Duplex.
As long as I keep the pulseaudio volume control running my external sound card works flawlessly.
For now, I just added PulseAudio Volume Control to my startup applications list.
The easiest way to do this is to start the Startup Applications application (System -> Preferences -> Personal -> Startup Applications) and drag-and-drop PulseAudio Volume Control (Applications -> Sound and Video -> PulseAudio Volume Control ) into the Startup Applications window.
If I find a more elegant solution, I'll let you know.