While I understand the need for a device to remember the last volume setting, doing so after a hard reboot seems a bit excessive, especially when PS Audio equipment is designed to be left on. That said, I understand that some do completely turn their components off regularly, for whatever reason.
However, I personally have never, ever purchased a piece of electronic equipment that defaulted to full volume upon (very) first power-on. It is simply not a good practice for an audio equipment manufacturer to follow. I’m sure it happens regularly, but I’ve never seen it.
Perhaps the easiest solution is have the technicians set the volume before shipping. And the best solution would be to make it a user configurable setting. It seems like a very easy to implement solution.