What is ?aptX? for Bluetooth speakers?

aptX is a digital audio technology which enables streaming of high quality (CD-like quality) stereo audio over Bluetooth connection between the Bluetooth source device (such as a smartphone with Bluetooth feature) and a Bluetooth ?receiver? device (such as a Bluetooth speaker). To enjoy the high quality music streaming with aptX technology, both the ?source? device (such as a smartphone) and the ?receiver? device have to be equipped with aptX technology. You can get more information about aptX from this site: http://www.aptx.com/ .