The Singing Machine SML633 Instruction Manual page 7

Connection
Connecting to AC Power
Connecting to LINE IN Jack
To External Unit
AUDIO OUTPUT
/ HEADPHONE JACK
Insert the AC power cord into a
conveniently located AC outlet having
120V AC, 60Hz.
Note:
Make all connections before connecting to
AC power.
Connect an external device by using an
appropriate cable (3.5mm audio cable not
included) as shown.
Note:
See page E19 to select and use the Line
In function.
— E6 —