Problem K4003

I configure the amplifier K4003. Two days the amplifier works perfectly.But after two days i put on and a clic and smoke cames from the TDA2616.So end of the IC.
What can be the reason. The isolation between ic and heatsink was oke.
Perhaps question of oscilations, or a bad and not stable TDA2616

Where can i buy a new TDA2616.

Your Velleman distributor can order one for you.