If you're using a Raspberry Pi and notice the output isnt totally clean, some USB Audio adapters don't like USB-1.2 and produce crackling in the output. You can work around the problem by adding
dwc_otg.speed=1 to /boot/cmdline.txt and setting the USB ports to USB-1.1 mode.
You can get user access to the audio hardware with other devices by granting access using
sudo usermod -a -G audio username