The Singing Machine groove XL Instruction Manual page 7

Connection
Connecting to AC Power
Cradle
Insert the small end of the AC adapter
into the DC IN jack on the rear of the unit.
Insert the other end (with the 2 blades)
into a conveniently located AC outlet
having 120V AC, 60Hz.
Note: Make all connections before
connecting to AC power.
— E6 —