The GMA-340 has two stereo entertainment inputs, Music 1 and Music 2. Music 1 is soft-muted during all aircraft radio activity and normally during ICS (intercom system) activity. Music 2 is a non-muted input. Two headphone outputs of these devices are used and plugged into Music 1 and Music 2. Two 3.5mm stereo phone jacks should be installed in a convenient location for this purpose.