Turn off the preamp but leave the power amp on. Does the speaker pump now? If not, I suspect you have an unstable preamp that is defective.
I do not know if your speakers were damaged by the initiation of the preamp but the cone movement of the speakers does not suggest it since they cannot move on their own.
I do not know if your speakers were damaged by the initiation of the preamp but the cone movement of the speakers does not suggest it since they cannot move on their own.