which damping factor is better for my speakers?

HI, ( excuse some mistakes in writing, i´m a spanish speaker)
My question is.... I have a Nakamichi Pa 7 power amp and a pair of KEF ref. series 105-2 , but I´ve seen that i have to turn a lot the knob of the volume of the preamp(threshold fet one ) to hear as loud as I like to.
someone told me the dampin´factor for this amp is 60, but says that it has too much power for the speakers as they are too eficcient. i´m confused, above all if once while hearing at some high level ( not to break my ears ), the leds of both the power amp and speakers turned On !. Is this normal?
On the other hand , some times I hear a sound comming from the amp, like if a metalic piece would crash agaist other, Imagine you take a small screw and throw it on the surface of the amp. This is the sound . It happens almost 4 times in the period of an hour. Is this related with the increase of heat iside the machine ? or what?