How long is the transmission range? 50 meters, 1km? John July 02, 2018 23:47 Updated Follow The Soundfly Aux can transmit up to 10 feet from the FM radio. Related articles What is the best format for the Soundfly to use (NTFS, FAT32, etc.)? How can I access the Fast Forward and Reverse functions using the controls on the unit (without using the remote). 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? Does it support and transmit in stereo from USB, SD card and aux in? What is the difference between this model and the Soundfly AUX FM Transmitter? Comments 0 comments Please sign in to leave a comment.