Sean is correct. More speakers get damaged from underpowered amps than from overpowered ones. The amount of power delivered to the speakers is dependant upon the voltage delivered to the speaker, which is dependant upon the volume control. If you play the speakers at a comfortable level the big amp will not harm them in any way.
The heat generated by an amp is mostly caused by the current in the output stage. In a pure 'Class A' design the output current is at a very high level all the time and thus the amp is hot all the time. In a 'Class AB' design the output current is at a low level unless a lot of current is being delivered to the load. Under low listening levels or with very efficient speakers the output current is small and the heat being generated is also small.
Chris
The heat generated by an amp is mostly caused by the current in the output stage. In a pure 'Class A' design the output current is at a very high level all the time and thus the amp is hot all the time. In a 'Class AB' design the output current is at a low level unless a lot of current is being delivered to the load. Under low listening levels or with very efficient speakers the output current is small and the heat being generated is also small.
Chris