I have a couple of Studio Projects VTB1 mic pre's. They don't have an
on/off switch, you plug them in and they're on.

However, when turning them off i.e. turning off the power strip they're
plugged into, I notice that the level meter slams into the full/max red
zone. It doesn't matter where the input/output gain controls are set,
does this every time.

Is there any reason to be concerned about this? They seem to work fine
so far, but I cringe every time this happens. Obviously I have to be
able to turn them off and the manufacturer hasn't provided any other
way to do it.

Is this normal and nothing to be concerned about?

Thanks for all shared wisdom.