Can I use a mini plug and run a cable from my Xantech cnnecting block directly into the back of the 990? Currently I am using an emitter stuck on the front.

The 990's IR input requires a 794-10 interface module to work with the output of a Xantech connecting block. I've got a similar Xantech system, and I've been using an emitter on the front since May 2005 because I'm too cheap to get the interface module...