Update: I suspect it's this issue here: - http://askubuntu.com/questions/537166/usb-audio-device-not-fully-working-after-hotplug - https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/841433 Basically, Pulseaudio is getting ahead of udev, so the device isn't configured by the time Pulseaudio tries to enumerate it.