Getting soundly to work on Ubuntu (KDE version)

Get the hardware and plug it in. ^[19]

Make sure you've got sound support at all: see whether the sound card is listed in the system settings (K->System Settings->Sound) (I'm using the KDE). Select the device you are using as the default device for all activities.

Get POC: try to find any application that will work with your headset. Ekiga (apt-get install ekiga) is one that will offer a menu to pick sound devices from, both for input and output, regardless of default KDE settings. Its configuration druid can be restarted from the menu too :)

When you've got sound in Ekiga, find which devices it has open. Find the pid with ps axu|grep [e]kiga and list the open sound devices with lsof -p <pid>. Save these for later reference.

Firefox by doesn't heed the default set in the KDE sound configuration. However, saying alsasoundconf set-default-card 1 fixed my case. If firefox is still using the wrong device, you might want to have a look here.

If the above doesn't help, you might want to cat /proc/asound/cards to find out which values to set in a ~/.asoundrc file:

pcm.!default {
type hw
card 0
}
ctl.!default {
type hw
card 0
}