Fun concept!
It was kinda hard tho. I am wondering how well it would work if the numbers in each amp were displayed without interruption for better readability and comparison with the notes. Altho, maybe that's exactly what you want, in which case I would suggest to stop or lessen the amount of tampering each amp gets if they have already been screwed, in order to give the player more leeway to get back on track.
Overall nice stuff! Kickass music as well!