I started to rechedule the cables of my system and I noticed that my Monitor Audio RXW-12 subwoofer is producing considerable amount of heat at the back above the power supply. I never noticed that over the years. The subwoofer usually remains connected to electricity in stand by mode and is triggered by the Denon 4310 AV receiver. Is it normal that the subwoofer is producing quite a heat at the back even in the stand by position? I searched on internet and found no answer. Can any of happy owners of MA subwoofer try theirs and let me know?