So, I have worked on this a little more in case anyone is interested. It turns out there is a LOT of overlap in the functionality of a DAAP server, and the DACP server needed to talk to iPhone Remote. In a sample 3-hour session of regular use, 76% of the traffic between iPhone Remote and iTunes on the mac were “databases” calls–the bread and butter of a DACP server. I am now starting to think the right course of action is to implement support for the particular database calls that iPhone Remote makes in an open DAAP server (I work in forked-daapd, but the principle applies to Firefly too), and then add in a module (perhaps a plugin) that responds to “ctrl-int” requests by sending commands to the player via RAOP. And, of course, the pairing, but that should be fairly trivial.