The man is right, you will want 2 in the end lol.
I am getting an 9 power soon, and will add the psx-r onto that instead.
Cyrus make the boxes so small, so that you can get 2 in the same space a noral amp / cd player takes, which means if you only have one, it leaves a dirty big hole on the rack, where another one could sit.... Watch out, the boxes multiply quickly, then your onto mono x's etc...
Try the cyrus unofficial forum as well, a wealth of knowledge on all these small breeding boxes!