The USB functionality of the BR-1600CD was to import and export WAV files as well as backup and recover projects. The BR-1600CD was not an audio interface and could not pass audio via USB in real-time. Also, due to the age of the product, the BR-1600CD was last compatible with Window 7 and Mac OS X 10.15.
To pass audio in real-time into computer recording software, you can connect the stereo LINE OUT of the BR-1600CD into the stereo input of an audio interface. Roland designs a variety of audio interfaces that can accomplish this. You may view audio interface information by clicking on the link below:
Roland Audio Interfaces
If you would like to export tracks that are recorded on the BR-1600CD to a computer as WAV files, the Track Export function can be used to burn WAV files to a CD. The WAV files can then be transferred from the CD to a computer. Please note that a computer CD drive is needed. Details regarding Track Export can be found on page 210 of the owner's manual.