K8060 will hot

Hello , I have the following problem. A K8060 is built in bass in a 5.1 system . I left on last night without a signal and it is burned and was very hot. I realized when no signal comes on it is very hot in one hour. If I send much bass from Receiver its worket very well, and its cold. When i stop the bass Signal its will hot. Why?
Thank you

Its worket about 5 Weeks every Day, and now:

Thats for 5 Weeks


I want to buy another one, but what when its happen again?