I have not yet received my 890 pro - it comes tomorrow. However I can tell you what I have learned. If you google 890 reviews you should find professionals reviewing the device and they explain the RF extender.

From what I read you will get a RF extender that runs off of AC. You can plug in 3 sensors that will point to the IR "eye" on your components. Each one can control 2 devices. The remote sends an RF signal to the extender (through walls and such) and it sends an IR signal via the cables to the components.

Also from what I read each time you make a change to the remote and hook it up to the computer you will also need the extender. So install it in a place that is easy to get to. I might set it up for a few days without the RF to play with and then add the RF. That way if I have problems I should be able to determine if it is a program issue with the remote or an issue with the RF set up.

Hope this helps. I will write back in a week, hopefully with a success story.