wrote:

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.

Yes, all equipment with single-ended electronics do this. You're seeing
the capacitors discharging unequally. Some give a similar thump on
power up. You worry too much.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."