My Sonus Faber Amatis have weak bass even though I'm running ML 536s--800 w/ch into 4 ohms

I don't know what I'm doing wrong. I thought the new monos would solve the problem. I still have to use subwoofers to feel like my system has any bass. I've tried speaker placement but to no avail. I realize it could be room issues, but short of packing my room pull of room treatment, there has to be something else. The drivers work, it just doesn't sound full. Should I get a different speaker? At this price, I expected more.