How many speakers will the DJ be using and what is the power output of the rig?
For the average venue with around 100 guests, a pair of 200-300 Watt speakers are usually sufficient. For larger venues, the DJ should be able to advise you on what is required. No-one wants to be deafened by the music, and on the other hand all the guests want to be able to hear it. A good DJ should be able to gauge the level at which the music should be based on the size of the room and the number of guests. He should be able to see if guests are uncomfortable or having to shout at each other. Some DJs may use “Bass Bins” which are a second set of speakers usually sitting below the level of the main speakers. Bass Bins offer a much more thumping rhythm and tend to be used more in clubs or for events where a lot of Club / Dance type music is expected. Again, ensure the quality of the speakers being used. Reputable manufacturers include Peavey, Cerwin Vega, Wharfdale and many more. If necessary do a bit of research on the internet.