However it might not be that as the red LED next to the button is turning on and off when I press the mute button. I might not have mentioned that earlier.
With my MCL2AV in ‘stand-alone’ (just power, iPhone input to TAPE and speaker connected), the LED just flashes as I press the sensor’s Mute button – it doesn’t stay on. The LED comes on permanently when I switch the MCL2AV off with the remote.