Hi,
For example, on the Oppo DV-980 or DV-983, audio files will play through the USB 2.0 input . However you have to make sure that the device connected is a FAT or FAT 32 file system, the Oppo will not read NTFS.
You will need to have a monitor connected to the unit to scroll down the directory tree of your files to play.
Also, it will only playback compressed files such as MP3 or WAV and some others that arent popular. No Flac!