High Quality Content by WIKIPEDIA articles! A Radio Pack is mainly used for musicians such as guitarists and singers for live performances. It is a small transmitter that is either placed in the strap or in the pocket. The transmitter box is connected to an amp or PA system and the user simply connects the receiver into the instrument. This means that there is no wires in the way. By using a wireless system, musicians are free to move around the stage. This has meant that more elaborate stage shows are now possible, with musicians performing a long way from the amplifier or speakers.