If the Speaker A/B light on the front panel of the EXA100 is flashing blue, this means that the device is currently in mute mode. You will need to select the mute button on the remote control to take the EXA out of mute mode.
If the blue light is constantly on, rather than flashing, this means that the A1 Power Amp Mode has been selected via the Power Amp Mode switch on the rear of the EXA.