I thought this state of mind was mandatory here?
Ken, obviously you had a physical connection issue with the Bouder BUT before you further judge the amp to be at fault, consider your upstream equipment. You may find that the Boulder simply powers down slower than the stuff ahead of it. Particularly if the equipment is op-amp based and has soft power supplies, i.e. minimal energy storage vs. load current. This can be a source of turn on and turn off transients.
Disconnect the inputs to the Boulder and see what happens when you remove power.