This is probably a very late response after 3 years. I own an Amplifi 30. 2 years ago, my amplifi had the similar problem. I plugged the headphones that would stop the noise (although it would come to the headphones). But then I chose to reflash the firmware (2.26.0, if I can still remember). Guess what? The problem was gone after reflashing!
However, my amplifi is having another problem: power button. Every time when I press the button to switch it on, I could see the LED flash (supposed to be on) and it turns off! I have to turn on, turn off, turn on, turn off. After trying numerous times, it could eventually be on. Not sure if it is due to power button issue or what. Having local reseller to fix the amp is damn expensive... :(
