If you want to hear your bass, check out the Mixer option from the Pause menu. This feature is available when you connect your bass to the device you use.
To access the Mixer, tap or click anywhere on the song screen and select Options from the Pause menu.
Browse through the different virtual amps to find the sound you love. Adjust the Volume to control the strength of the sound and Gain to set the level of distortion in your tone.
To optimize the signal between your bass and the virtual amplifier, select Calibrate and follow the prompts on the screen.