Quite so: and the limiting factor on the 660AV is having the Nubus adapter, which also has the DAV connector on it.

I would like to see a better photo of the adapter without the Nubus card if that's at all possible

The Nubus card itself doesn't look like any that I'm familiar with, but as suggested you may be able to ID it in another Nubus machine. Or by trawling through the images at the Applefritter Nubus Mafia page for a match.