Update (for those who might consider doing something like this): I just called. The guy was friendly and professional, but I learned that all the old equipment belongs to the school system and, once it’s retired from active service, will be sent to the Division of Maintenance.
Oof. This might be the end of my adventures. Not sure it’s worth my time to go through so many layers of bureaucracy. I’ll do a little more Googling before I call it quits. (FWIW, I already have some “version 2” Audiosone amps that are pretty darn similar to the ones at the school, so it’s not like I haven’t already gotten my voice evac fix!)
Thanks again, everyone!