depending on the size of the hall, you could just rent a PA system which would have enough juice to throw out whatever music you play. a home stereo, no matter how powerfull, is not going to be able to compete with a full blown PA system because the drivers and tweeters of the smaller rig just won't be able to physically project enough - that is, considering the hall is open and has very few places for sound to bounce on. also, the frequency capability of a PA system is going to complement your dance music better- better bass, treble, and mids will be better heard on a larger, more powerful system. during my DJing days (i still Dj but not as much as I used to) in the era of warehouse guerilla house parties, the PA systems used to be monstrous to compensate for the size of te venue, and just simply project a better sound. the PA system, though basic, was pretty good and was made up of a small mixer, speakers, and the power amps. the usual array of turntables, DJ mixers, Cd players, and effects were the usual methods of playing music.
sidenote: the rig had to be somewhat portable too. afterall, these were guerilla house parties. ah, house, trance, progr, and urban techno....those were the days:) nowadays, things are more posh and civil with all the music inside clubs, pumping through fancy systems and catering to the martini drinking crowd.