Mirage s8 subwoofer is emitting a constant hum

That is just the radio from the input,its normal

My sub doesn't hum all the time, but it's been flaking out (weird bass drops and sometimes no base at all). Opened it up today (removed speaker by removing the hex screws holding it in place and found a small 250v glass tube fuse on the main board that was all but burned out. Replaced that and it seems to be behaving again. I guess I'll keep a few spare fuses around just in case, but they're pretty cheap and replacing one only takes about 5 minutes if using a power drill to remove the woofer screws and put them back in place.