Unplug the preamp for a few minutes.
Just the preamp should do..
Then plug them back in.
Often the internal 'logic' can 'go crazy' and get stuck. Unplugging them can allow it to untangle itself.
If it still does not work. Then check in the owner's manual to see if the preamp has a special set of functions to reset the preamp.
Usually it is holding one or two extra buttons when you turn on the item at the powerswitch on the item.
Just the preamp should do..
Then plug them back in.
Often the internal 'logic' can 'go crazy' and get stuck. Unplugging them can allow it to untangle itself.
If it still does not work. Then check in the owner's manual to see if the preamp has a special set of functions to reset the preamp.
Usually it is holding one or two extra buttons when you turn on the item at the powerswitch on the item.