content: TBH, they've done a good job with both USB and BT audio. As long as the USB plug is backwards compatible and the audio drivers standardized, I can take my old USB1 soundcard and connect it to my android-on-a-stick and get audio. As long as the A2DP-profile is supported and BT continues backwards compatability I can take my old BT headphone and connect them to my brand new BT4 phone. If there were an industry standard ala the 3 channel minijack for USB, the standard could be good for 20+ years, at which time we'll get the music beamed into our brain.