Andrew, I think the Height and width channels (supported in the denon 4310 and other receivers) are simply utilized by audyssey. There are no dvds that I am aware of that actual have sound specifically for these channels. Instead audyssey somehow magically extracts bits and pieces from other channels perhaps and plays them through these channels... I am not sure of the details. I wouldn't worry too much about running speaker wire for these if you don't think you will ever use it.

-David