I've been researching this for over 18 months (on and off) for maybe one of my Northern Connection articles.
without too much luck on Ann herself, i have to say.
Armco to American Sound Corp to Ardco (allied record dist co) to CIRCA (consolidated international record co america) - are the distie/label clues to follow, but these and other non-Ann stuff is all i have at the moment( and expect ever to get).