Grace Digital GDI-BTPB300 3play Quick Start Guide - Manual (Page 14)

The 3 devices below are paired to 3play indicated
by the illumination of the 3 blue LEDs on the front
of 3play. Device 1 is playing music while devices 2
and 3 are paused.
When play is pressed on either device 2 or 3 while device 1 is
playing music, device 1 is paused allowing device 2 or 3 to
play music.
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