I wasn't at the last training, but I am guessing Jeff from Denon said something along the lines of what's on the Denon web site HDMI FAQ:

[Link: usa.denon.com]

I refer to this link all the time...I get questions about HDMI connectivity a lot, and not many people consider that their problem might be the U-code portion of Annex A of the repeater conformity specifications of the HDMI protocol.