My subwoofer from Hifonics makes noises and I don’t know if that’s normal. The level or gain of the output stage is 6/8. So close to Max. but the subwoofer has much more power than the output stage. So the subwoofer can’t normally be “overburdened”. I couldn’t notice this noise in my previous installations. Click here for the video: https://www.youtube.com/watch?v=l3rteibelow