when i first used AA, i thought that as well but from my experience (with the new Mazda's Bose and BMW's Harman Kardon w/ iDrive 7) i think it actually routes through the USB and/or WIFI-Direct (For Wireless Android auto) considering that in both cars, the BT is registered to only be used for telephony with music audio disconnected when AA is connected. and i can definitely hear the difference with AA vs BT. Though question is, is does Poweramp stream hi res to AA or is it stuck with the standard 16/44.1khz mode?