Well, you would need a one zone connecting block. Just use a simple one zone block and run all the IR receivers into its input. Then run all the IR out to the gear, if the Denon has an IR in for the multizone controls you can try to use that, but you may need a interface from Xantech also for reliable operation.

Be sure you teach your other rooms remotes the multizone control codes, or you'll change the main rooms source also. The only reason you would need a 2 zone connecting block is if you had seperate sources for those zones. But since it sounds like you'll be sharing sources between the zones, and the remote zones will have the same audio source playing, then you only need the single zone connecting block.