Get the sub, put it on a subdude from Auralex an just be mindful of the levels (or lower the gain). I lived in apartments and condos for years, with dual subs for a large part of it, and never got evicted. What you gain with a good sub is far more than a potential request or two to turn it down.
Augustine's Law: "The last 10% of performance generates one-third of the cost and two-thirds of the problems."
"If it works the first time, it's not high end." ~ Harry Pierson