When I use my interface in OS X for Quicktime, Windows Media Player, or Real Player, I hear digital noise
Goto /Applications/Utilities and launch, Audio MIDI Setup. If you are using 10.3.X, click on Configure Speakers. Check to make sure you are using a 2 channel stereo stream, such as Stream 1, Main Outs for the 828mkII and 896HD. If you are in 10.2.X or below, make sure you are outputting out of a stereo stream, such as Main Out or S/PDIF.