Thanks,
Dissipated power at full power is 10W, so not much. I will use a metal case and I thought of using it as a heatsink. But it would imply that the IC would be on the bottom of the board, and other bigger (taller) elements (like filtering selfs) on top of the board. Is this a good idea for a class D design ?
Thermal epoxy sounds like an option, I didn't know it was so strong, I'll give it a try.