Hi Marcus,
having posted the same question regarding an ATV-Avant a few days ago, I will just do a further comment.
In my opinion, the converter you are looking converts only Component-to-RGB. Make sure that the AV2 Expander port of your MX7000 can manage RGB signal (opposed to composite only). In this case, you would need another type of converter (see my post).
Cheers. P.