I've use a trusty older pair of VMPS Super Tower R speakers for party use. The crowd's ears will usually give out before the speakers do.
Your most cost-effective option would be to simply rent a dj speaker setup for the night. 900 square feet with a low ceiling like yours would not take a lot of pro audio to get the boom. A couple of 15" or 18" based Cerwin-Vega/EV/JBL towers with 200 watts per channel would be more than sufficient.
Your most cost-effective option would be to simply rent a dj speaker setup for the night. 900 square feet with a low ceiling like yours would not take a lot of pro audio to get the boom. A couple of 15" or 18" based Cerwin-Vega/EV/JBL towers with 200 watts per channel would be more than sufficient.