I am running USB Server on RasPi2 and Client part on Ubuntu Mate 15.04 64-bit (with latest updates). I have an old (purchased about 10 years ago, no docs, no nothing) USB audio adapter that normally is plugged into Ubuntu host as the main audio device.
I played with USB Server running on Pi2 with USB keypad (wireless keyboard + touchpad with USB dongle) attached and it worked like a charm. I used GUI Linux client running on Ubuntu with root privilege and was able to use that USB keypad to control Ubuntu desktop.
I then plugged USB audio into Pi2 (after closing previous session and rebooting Pi2) and attempted to attach Ubuntu box into it following the same path. When I selected "USB Audio" in the list of devices displayed in Linux GUI client, my Ubuntu box halted. Actually it got frozen: monitor was showing the last screen, it did not react to keyboard and mouse. I could no longer control it and had to shutdown it by pressing power button for a number of seconds.
I repeated this experiment several time (Pi2 has also been restarted every time) and it was consistent.
I don't have much of experience in debugging such situations. My best guess was to look at syslog file just before it started the new session. The last things that I can see there are enclosed below:
Oct 17 22:30:55 ocean dbus: [system] Activating service name='org.mate.SettingsDaemon.DateTimeMechanism' (using servicehelper)
Oct 17 22:30:55 ocean dbus: [system] Successfully activated service 'org.mate.SettingsDaemon.DateTimeMechanism'
Oct 17 22:31:14 ocean kernel: [ 61.068468] usbip_core: USB/IP Core v1.0.0
Oct 17 22:31:14 ocean kernel: [ 61.073173] vhci_hcd vhci_hcd: USB/IP Virtual Host Controller
Oct 17 22:31:14 ocean kernel: [ 61.073181] vhci_hcd vhci_hcd: new USB bus registered, assigned bus number 3
Oct 17 22:31:14 ocean kernel: [ 61.075956] usb usb3: New USB device found, idVendor=1d6b, idProduct=0002
Oct 17 22:31:14 ocean kernel: [ 61.075962] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
Oct 17 22:31:14 ocean kernel: [ 61.075965] usb usb3: Product: USB/IP Virtual Host Controller
Oct 17 22:31:14 ocean kernel: [ 61.075969] usb usb3: Manufacturer: Linux 3.19.0-26-generic vhci_hcd
Oct 17 22:31:14 ocean kernel: [ 61.075971] usb usb3: SerialNumber: vhci_hcd
Oct 17 22:31:14 ocean kernel: [ 61.076398] hub 3-0:1.0: USB hub found
Oct 17 22:31:14 ocean kernel: [ 61.076420] hub 3-0:1.0: 8 ports detected
Oct 17 22:31:14 ocean kernel: [ 61.076788] vhci_hcd: USB/IP 'Virtual' Host Controller (VHCI) Driver v1.0.0
Oct 17 22:31:14 ocean systemd: Starting Stop ureadahead data collection...
Oct 17 22:31:14 ocean systemd: Stopped Read required files in advance.
Oct 17 22:31:14 ocean systemd: Started Stop ureadahead data collection.
I could re-run experiment to retrieve some other logs if needed.
Is there anything that I can do to setup USB server/client to make it compatible with my USB audio? Thank you.