I had a similar quandary when I was setting mine up. Both my HD cable box and the 990 refused to work with my very basic Xantech IR setup, and while I never dug into why the HD box didn't work I did ask Outlaw about the 990. Scott looked into it and reported that the 990's IR input requires an interface module, specifically (for Xantech) the 794-10 interface module. Hope that helps.