[LAU] Xfce, jack, and GStreamer

I'm running Debian Sid and have just installed Xfce. I'm having trouble getting Xfce's audible alerts to work. As far as I can see, they're the only sounds on the system that want to go through GStreamer. Sound is through jackd2 and FFADO to a Saffire PRO 24. Jack is set up as described in http://alsa.opensrc.org/Jack_and_Loopback_device_as_Alsa-to-Jack_bridge (That website is currently unavailable. It would sure be nice to have another copy of that page for reference. A copy of the .asoundrc is here: http://pastebin.com/1WLtqeJ1 ) Programs that speak directly to jack work. Sound in Flash videos such as Youtube works. "speaker-test -c2" works. "gconftool-2 -R /system/gstreamer/0.10/default" shows: chataudiosink = jackaudiosink buffer-time=2000000 audiosink = jackaudiosink buffer-time=2000000 videosrc = v4l2src visualization = goom audiosink_description = Default musicaudiosink = jackaudiosink buffer-time=2000000 chataudiosink_description = Default audiosrc_description = Default audiosrc = jackaudiosrc musicaudiosink_description = Default "gst-launch audiotestsrc ! audioconvert ! audioresample ! jackaudiosink" produces a tone in the left speaker. So does "gst-launch audiotestsrc ! audioconvert ! audioresample ! autoaudiosink" When I run xfce4-mixer, I get an error message: "GStreamer was unable to detect any sound devices. Some sound system specific GStreamer packages may be missing. It may also be a permissions problem." When I try to get an audible alert from, for example, the Orage calendar program, there is just silence. What am I missing? Or am I barking up the wrong tree?