I'm running Funtoo Linux, a Gentoo derivative.  My two new Plantronics USB headsets (one wired, one wireless) work nicely.  I plug one in, ALSA notices it, and if I manually set an application to use it instead of the default devices, it will.I'd prefer to simply have the headset become my default input/output when present, and have the default revert to my on-board speakers otherwise.  How do I automate this kind of switch?
How can I switch to my USB headset automagically when it's plugged in?
linux;usb;alsa;hot plug;funtoo