What home stereo can fill a larger room of 140 people during dinner?

I am having a wedding reception where my friend is making playlists on his itunes to serve as backround music during dinner. The reception will be the fairly large Swedish American Hall that has a 384 person capacity. Instead of renting a pa system, I want to just buy my fiancee a stereo she can use after the wedding. What is a good stereo and how powerful does it and it’s speakers need to be to work for up to 5 hours of music? We also have a live band – this is just for background music during dinner and for lounging around with 140 people. It would need a digital in.