Okay, it took two flash bits -- one for AC, one for DC -- I just assumed that there'd be howls of misery if this feature didn't remember AC/DC separately.

To use it, look for the "Volume Level on Boot" entry on the Hijack menu (long knob press). If you cannot figure it out, too bad!

EDIT: Hijack v317 is out now, but wait for v318 which fixes a typo on the menu display.

Cheers