Controls
Short answer
The Marshal Emberton II speaker controls turns the speaker on/off and it also control if you play/pause your music as well as the sound adjustments.
This is how you use the control knob:
Push and hold for 2 seconds to turn on/off.
Push once to play/pause.
Push right/left to skip forward/back.
Hold right/left to fast forward/rewind.
Hold upwards/downwards to adjust the volume.