As near as I can tell, The problem is In the preamp or earlier. If you switch to a different input does the problem go away? If so, it may be in that input stage in the preamp or, more likely, it is in the source connected to that input. So move that source to a different input position in the preamp and see of the problem follows. If the problem occurs no matter which input you select without moving the source, then it is likely in the preamp. If it follows the source then it is likely the source or the cable.
If you can try different cables, that might be a fast and easy fix. If not, do you have another preamp that you can swap out such as a Magni or something?
I assume you have shut everything down for a few minutes to let your components forget their troubles. I once put a Tyr into protection mode and only shutting the power off and unplugging it for a few minutes got it happy again.