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? Instruction Guide What is the difference between this model and the Soundfly AUX FM Transmitter? What is the best format for the Soundfly to use (NTFS, FAT32, etc.)? What is the best way to store MP3 on the the SD card / USB Stick to get the maximum number of tracks? If i was to save each CD in its own folder am i right in thinking i could only have 99 CD's on each SD card or USB stick? Comments 0 comments Please sign in to leave a comment.