There's an Electronics Expo on Route 18 and another in Woodbridge. Both have pretty demonstration rooms, but according my parents (based on my system), sound like crap. But you might as well take a look since audio shops in NJ seem few and far between.
6th Ave. is on Route 18 as well, and seems like a place worth visiting if you are into Paradigm...but the last time I went there, they were incapable of even turning their audio systems on...
There's also a place called Hi-Def of Freehold, which I haven't been to yet, carrying higher-end stuff like Rotel.
PS: Deftechs are awesome if want colored sound and have no respect for the original intention of the sound mixer.