Hi Thomas, Thanks for your support again - i got it working now! You were right, the interface have to be exact in that order you supposed below. I had a HID device as interface 3 and the midi-device was interface 4 - this it NOT working, even NOT if you put the right numbers into the AC Class Header DSCR, so a least I tried to change these numbers and: It works ! -daniel -----Urspr=FCngliche Nachricht----- Von: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] Im Auftrag von Thomas Zepf Gesendet: Mittwoch, 2. April 2003 21:11 An: wdmaudiodev@xxxxxxxxxxxxx Betreff: [wdmaudiodev] Re: USB-audio and USB-midi at same time with standard devices under WinXPproSP1 > Now I added the descriptors for a standard midi device - so everything > works fine, BUT the AudioDevice (the 'real' audio device and not the=20 > MIDI-device named "usb audio device") causes an error in the device=20 > manager! >=20 > Midi works fine...has anyone an idea what happenend ? >=20 > Does Win XP support usb-midi and usb-audio at same time ? Perhaps it=20 > is a windows bug ? Yes Win XP and Me with QFE supports midi+ audio via USB. I have done this and it works. Check your AC Class Header Descriptor for correct size You will need 4 Interfaces Interface 0 for AC Controls Interface 1+ Interface 2 for Audio streaming Interface 3 for Midi Thomas=20 ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: = mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=3Dsubscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=3Dunsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/ ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/