Significant difference??

Denon and Marantz maybe "under one roof" but so is McIntosh but I believe most would agree that McIntosh is better made and has superior sound.

D&M Holding owns Marantz, Denon, and McIntosh, as well as a few other companies. Before 2002, Denon was a separate company.

I know they share a lot of the same parts (that's how you keep cost low), Denon and Marantz have seperate design philosophies and some of the features may only be avaliable on a Denon but not on the Marantz (at least at first), however I do not know if they are actually made in the same factory.

I do not think there are any significant differences between the two.

If you are looking for a surround sound processor and don't care about HDMI then I would suggest looking for a McIntosh MX119. You won't get the HDMI inputs or the HD video switching but it would probably be better anyway if you run your HDMI directly into your TV. For audio let the Blu-ray player decode the HD sound via the Analog 7.1 outputs to the 7.1 inputs on the McIntosh. These usually sell for right at 2K or less and like all McIntosh gear, it was built like a tank. For solid state it is a wonderful sounding Pre/Pro.