You'd think that everything would be just fine since the computers are on UPSes but for some weird reason, the drive in the file server that serves media to the Squeezeboxes got in a weird state that required a full sever powerdown to clear. After fixing that, I had to troubleshoot why the Squeezebox in the living room would play but no audio would come out of the speakers... Finally, after shutting down the whole audio chain (Squeezebox in the living room, DAC and amplifier in the server room) and restarting it, things finally got back to normal. Clearly, I should have thought about a remote reset mechanism for this (or set up a system with fewer moving parts).
Well, that wasn't fun.