Zoom AMS-22 Operation Manual page 25

3.
Connect an instrument or mic. (→
4.
Adjust the input gain. (→
5.
To use BGM from another device, connect it to the LINE IN.
HINT:
BGM can also be played back on the smartphone/tablet and looped back by USB.
Connecting
Adjusting the input gain)
instruments, Connecting
25
mics)