As part of its Concept for Android program, Sony has started pushing out a new update to participating Xperia X units. The update arrives as build number 38.3.1.A.0.74 and brings along a couple of major changes, including AptX support.
With the update (which is currently hitting the experimental track on Xperia X Concept), users will be able to enjoy hi-res Bluetooth sound using the AptX codec. In addition the update also includes Android security fixes for the month of March.
Source | Via