With any subwoofer the placement for best bass loading (most even response) may not coincide with the placement for best imaging from your monitor speakers, especially in a small room. Additionally the monitor speakers may not be at an optimum height. Other than this it should work OK. (I own a REL sub, not ACI).
Why do you wish to have two subs ? Could you get by with one and free up some space?
Why do you wish to have two subs ? Could you get by with one and free up some space?