Watch the Downward Inversion online guitar lesson by Brad Carlton from Chord Studies: i to V7 Vamps Vol. 1
We start with our Amadd9 in the ninth position, and be very careful to keep finger four upright so you don't choke string one by mistake. Then you simply move that voice down a whole step for straight ahead Am. Your first finger is going to be a guide as you move to your E7♭9, and then the other inversion of this chord is played down three frets.