You rent? Save your money. First, because really good bass requires four or more subs. So no matter how much money you spend or how good a sub you get it won't really matter because its only one. But second, because you rent, so the more bass the more problems. So your money didn't buy bass, it bought complaints.
Way better idea, what will not get you problems but will greatly improve your system, including even the bass: Total Contact, HFT, ECT, Orange Fuse, Cones. Transform your system in ways you will really appreciate but without doing anything to tick off the neighborhood.
The sub you have by the way is fine. Its the crappy plate amp inside it that's bad. All you have to do is find a suitable replacement. If despite everything I've said you're determined subs are the answer then Dayton makes a great sub amp. Get one now and fix your current sub. Then with the amp it will be a lot easier and cheaper to add subs one or two at a time until you get to four- which can all run off the one Dayton amp.
Search around. Swarm subwoofer system. Distributed bass array.
