Missing channels on usb audio device

[linux@xxxxxxxx (Robert M. Albrecht)]

Hi,

I'm trying to install the Terratec 6Fire USB audio device. It's an 
external audio device with several analog in & output channels.

The alsa-driver is running and I can play analog stereo music or movies
on pulseaudio based players.

I can output digital sound (ac3 or dts) on spdif via optical with vlc
and mplayer.

But I can't output analog multichannel sound from flac files or movies.
Although alsamixer can access all 6 analog output channels, pulseaudio
does not see them.

I'm running Pulseaudio on Fedora 16.

Currently I'm slighty lost, as I'm not sure if this is a driver, an alsa 
or a pulseaudio problem and how to troubleshoot this. Any help would be 
appreciated.

Regards,
Robert

[root at localhost alsa]# aplay -L
default
      Default
sysdefault:CARD=Intel
      HDA Intel, STAC92xx Analog
      Default Audio Device
front:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      Front speakers
surround40:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      4.0 Surround output to Front and Rear speakers
surround41:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Intel,DEV=0
      HDA Intel, STAC92xx Analog
      7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
sysdefault:CARD=DMX6FireUSB
      TerraTec DMX6FireUSB, DMX 6Fire USB Analog
      Default Audio Device
[root at localhost alsa]#

[root at localhost pulse]# aplay -l
**** Liste der Hardware-Ger?te (PLAYBACK) ****
Karte 0: Intel [HDA Intel], Ger?t 0: STAC92xx Analog [STAC92xx Analog]
    Sub-Ger?te: 1/1
    Sub-Ger?t #0: subdevice #0
Karte 1: DMX6FireUSB [TerraTec DMX6FireUSB], Ger?t 0: 6fire Analog [DMX
6Fire USB Analog]
    Sub-Ger?te: 1/1
    Sub-Ger?t #0: subdevice #0
Karte 1: DMX6FireUSB [TerraTec DMX6FireUSB], Ger?t 1: 6fire Digital Out
[DMX 6Fire USB Digital Playback]
    Sub-Ger?te: 1/1
    Sub-Ger?t #0: subdevice #0
[root at localhost pulse]#