I have mounted the kit carefully without the heatsink.
The problem i have is that during testing,
the IC TDA 2616 is heating up without being connected to speakers AND without input signal.
Is this behaviour normal? Should it heat up without input signal?
Please note that an amplifier should not be used without speakers connected and definately not without the heatsink.
The heat generated by the quiescent current of a class AB amp can destroy the IC, if used without heatsink.
THX for the quick reply. 
When noticing heat i turned it off.
I hope it did not have time to overheat. I shall connect it to the speakers and heatsink for further testing.