I've just completed an amp1b and want to check a possible power supply issue before testing. I have some memory of reading that the chip can fail if the 5v supply fails while the rail voltages are present - anyone confirm this? If so, would it be a good idea to have the 5v supply switch the main rail voltages on via a relay i.e. so if you lose the 5v you also remove rail voltages and chip is safe. Comments please.