Hi there, been having a strange problem with my creative HD usb dac. Most of the time it doesn't work on startup and doesn't show up in sound device list. Only when I unplug and plug it back in does it work. It does this in both 14.04 and 15.10.
I'm currently using 15.10
here is the dac in question: http://www.amazon.com/Creative-Sound-Blaster-System-Preamp/dp/B004275EO4
It only does this for this device, the realtek integrated works as far as I know. My mouse always works.
It's also interesting that when I was playing around with sabayon it kept reporting a usb error on startup and would not work until I unplug the dac.
Specs if needed:
I7-2600K
Asrock Pro4-m z77
Gigabyte HD 7950
Intel 600gb ssd
Samsung ddr3 1600mhz 4gb x 4
Creative HD X-FI USB