The 1U Bye Bye from EoWave is an input/output expander for the Supamix from the same company. It is the 1U version of the O phone/lineout in Intellijel format. The module supplements the Supamix with a stereo input (like channel 5+6) as well as a line output and a headphone output; both outputs are equipped with their own level control. 1U Bye Bye is connected to the back of the main module in order to fulfill its function.