Comment 6 for bug 579040

I think this might generally be related to USB Audio as I see the same behavior with my
Bus 003 Device 003: ID 0ccd:0028 TerraTec Electronic GmbH Aureon 5.1 MkII

pavucontrol shows only input devices for the soundcard but no output devices.
The interesting thing is, that aplay -l shows the Output device, but aplay -L doesn't

domdorn ~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: Aureon51MkII [Aureon5.1MkII], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: NVidia [HDA NVidia], device 3: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: NVidia [HDA NVidia], device 7: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: NVidia [HDA NVidia], device 8: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: NVidia [HDA NVidia], device 9: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

domdorn ~ $ aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
pulse
    Playback/recording through the PulseAudio sound server
hdmi:CARD=NVidia,DEV=0
    HDA NVidia, NVIDIA HDMI
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=1
    HDA NVidia, NVIDIA HDMI
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=2
    HDA NVidia, NVIDIA HDMI
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=3
    HDA NVidia, NVIDIA HDMI
    HDMI Audio Output

I'm currently running
domdorn ~ $ uname -a
Linux domdorn-laptop 2.6.35-22-generic #34-Ubuntu SMP Sun Oct 10 09:26:05 UTC 2010 x86_64 GNU/Linux

I also have lots of these entries in /var/log/messages
Oct 23 12:45:14 domdorn-laptop kernel: [ 26.817492] xhci_hcd 0000:0f:00.0: WARN: Stalled endpoint
Oct 23 12:45:14 domdorn-laptop kernel: [ 26.827369] xhci_hcd 0000:0f:00.0: WARN: short transfer on control ep

Oct 23 12:46:02 domdorn-laptop kernel: [ 88.967412] 3:1:1: endpoint lacks sample rate attribute bit, cannot set.
Oct 23 12:46:03 domdorn-laptop kernel: [ 89.270900] 3:1:2: endpoint lacks sample rate attribute bit, cannot set.
Oct 23 14:48:00 domdorn-laptop kernel: [ 7401.627430] xhci_hcd 0000:0f:00.0: WARN: transfer error on endpoint