Originally Posted by: light487The D9 makes sense actually because while I was fiddling around I noticed that I could easily substitute the Am7 for a CMaj, followed by a DMaj then a GMaj. It has a very similar harmonic structure to the progression.[/quote]
Very good observation!
[QUOTE=light487]An Am7.. is that all it is?

No, no! An A7, as in A Dominant 7 - a major 3rd and a minor 7th.

A7 (dominant 7)
A - 1 (root)
C# - maj 3
E - 5
G - min 7

A minor 7
A - 1 (root)
C - min 3
E - 5
G - min 7

The D in either chord is just a sus 4th.