Hello, We are developing USB audio device which will use generic usbaudio.sys driver provided by Windows 7. The device's USB descriptors define 5 input mono terminals (2 headsets, 1 microphone, 2 lines in) which use one isochronous IN USB endpoint to transport audio data from the device to Windows OS. When the device is connected, Windows reports 5 recording devices. What is a bit surprising to me is that each of the 5 recording devices has 5 channels and can be used to receive data from all 5 channels. What's more when one of the five devices is being used to receive audio data then an attempt to use other device ends with an error message "device already in use". Our device has the following topology (captured with ksstudio.exe): [http://social.msdn.microsoft.com/Forums/getfile/160724] Basically everything works fine and I'm just looking for confirmation whether the behavior described above is expected or are we using Windows' audio architecture in a way it was not designed (I mean we are misusing it) ? Thanks, Lukasz