The drivers in the G4 "Pro" speakers are the same as the Cube's. Apple used 2 manufacturers, but the specs are the same. There may be differences in paint color (white or silver) and surround color (dark or light grey) but they sound the same - or at least they did when new.

http://www.cubeowner.com/forums/index.php?showtopic=14123

http://www.cubeowner.com/forums/index.php?showtopic=13516