That is what Dolby Pro Logic does. The issue is that there is content recorded in 5.1 (Left, Center, Right, Surround Left, Surround Right, Subwoofer/Low Frequency Effects) but there is no way to play it back through the system so the only content you can play is 2 channel stereo. Proper imaging from 2 speakers should produce a “phantom center channel” so I just don’t get the need.