Foren
http://www.dsprelated.com/groups/c55x/1.php
USB-Specs
http://www.usb.org/developers/devclass_docs/
http://www.usb.org/developers/devclass_docs/usbmass-ufi10.pdf
http://www.usb.org/developers/devclass_docs/audio10.pdf
http://www.usb-by-example.com/FTDI_Book_C.pdf