@AaM Jay The AA speakers will do okay without a sub, they have decent low end (but not sub territory but then few speakers do that anyways). A sub in a typical apartment with crappy construction will likely be an issue with neighbors (now if you had cement walls/ceilings/floors....).
The 201s may not be great but they're paid for, as are the 161s. I'd simply save up for a while. I'm confused why the 161s used as surrounds (they're not rear surrounds in a 4.0 configuration) had anything to do with Atmos, tho.
ps You should have started your own thread....