If you won't your USB headset to be primary sound device when system boot,then you have to create a file in /lib/modprobe with that content
options USB kernel module index=0
options other card module index=1
To view which module is used by system run that command lspci -vvv
Sorry for my english
This is mine i have a intel audio card and creative sound blaster,my creative card is a primary device
options snd-ctxfi index=0
options snd-hda-intel index=1