I've had luck with controlling the multizone out of a marantz with using a Niles Intellipad with the Xantech 'transcoder' 794-00. Learn the multizone buttons into the Intellipad and go from there. Very reliable actually.

But if you have a higher spending limit, then I suggest AudioControl Director, or the AudioAccess stuff, VERY reliable. Or, if your on a tighter budget, then go with a second receiver and control it seperatly. The only concern then is source control...do you share them, how do you power them seperate from the main system, things like this. The systems mentioned in this paragraph have source sharing and powering capabilities...