"ADC Extension by Dr. Bott offers an extra 3 m (10 ft.), extending the range of the display to a total of ca. 4.5 m (15 ft.). A passive extension cable cannot go further than that as both the digital video signals and the USB signals that are also carried in the ADC cable will not permit so."
sound like you would need a divice that would bump up the signal in order to get it pst 15 feet, but hey my dorm is only 15 feet long.