As a fan of USB audio devices, something that has caused me dissatisfaction for a very long time in my Debian Linux desktop environment has been the inability to gracefully and easily switch between multiple installed sound cards.
I just installed the pavucontrol module and perhaps this is a thing of the past, at least for Gnome / Pulseaudio users. After installing pavucontrol I get a second loudspeaker / mixer icon in my desktop tray, which is a little confusing, and both mixers seem to interact and have some control over sound volumes. Not elegant, but the key addition inside the pavucontrol "Sound Preferences" dialog is an "Output" pane that lists my available audio outputs: "Internal Audio" and "Audio Adaptor" (USB headset), with a radio button beside each.
Clicking on the radio buttons transparently switches the audio back and forth between my laptop speakers and my USB headset. Outstanding.