Hello, I recently got a USB audio class compliant RME Babyface Pro interface. I previously posted about an issue getting all of the channels to work, but that ended up being an issue with PortAudio that is trivial to work around. Anyway, there is still the issue that the device's mixer controls are not detected by Linux. alsamixer sees no controls at all. The mixer controls must be accessible in the device's class compliant mode because the manufacturer's iPad mixer program can control its mixer and onboard DSP effects. I have attached lsusb -vvv output for the device. Below is dmesg output when the device is plugged in:

[191013.268711] usb 2-1.2: new high-speed USB device number 11 using ehci-pci [191013.355392] usb 2-1.2: New USB device found, idVendor=2a39, idProduct=3fb0 [191013.355403] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [191013.355409] usb 2-1.2: Product: Babyface Pro (70785713) [191013.355413] usb 2-1.2: Manufacturer: RME [191013.355417] usb 2-1.2: SerialNumber: 9399A998B9CB3C8 [191013.360347] usb 2-1.2: unit 2 not found!