Does it support and transmit in stereo from USB, SD card and aux in? John July 02, 2018 23:56 Updated Follow Yes, the Soundfly Aux will transmit in stereo from USB flash drive, SD card and aux in. Related articles Does it have any sound equalizer settings or option? What is the difference between this model and the Soundfly AUX FM Transmitter? Comments 0 comments Please sign in to leave a comment.