When you meet with your site, you will go over the set up of the room, where to put tables of guests, dance floor, bar etc. One thing that a lot of sites do not put appropriate thought into is where the DJ/Band's speakers will be in relation to the guests. To them it is all about the aesthetic of the room when guests walk in.
A lot of sites think it is a great idea to put the dance floor in the middle of the room and surround it with a circle of guest tables, with the DJ/Band setting up in a corner or the side. This is all well and good, but when we move to the dance portion of the evening, the music is going to get louder. Any guests seated between the DJ's speakers and the dance floor will not be able to sit there and hold a conversation. The likely outcome is that they will leave.
The site often doesn't care about this as the DJ/Band are the ones that will get the 'blame' but they should know better. The general rule of thumb is to not have any guests between the speakers and the dance floor, and any tables that will be close to the speakers should have younger guests.
This is nothing to do with the DJ/Band themselves, you can set them up anywhere. It is all about the placement of the speakers. Here are a few examples of poor floor plans.
The ideal scenario here would have been what we call the 'Horseshoe' effect where they would have had the DJ along one of the sides, with the head table (possibly on a riser) on the opposite side and a horseshoe of guests around the dance floor, which would be moved across so it was directly in front of the DJ . The reason I suggested a riser for the head table is that then you could put some tables of guests in front of them between them and the dance floor, but they would still 'stand out'.
This scenario would mean no tables of guests would be between the speakers and dance floor!
Where they had the sweetheart table was up against a plain wall. My suggestion was to rearrange tables as shown in Figure 4.
I hope this all makes sense. I stress, it is nothing to do with the DJ/Band, it is all about the comfort of the guests when the music gets louder for dancing. During dinner, most DJ's can provide wireless speakers that can be placed around the room to give a surround sound effect. This way you are not trying to reach the whole room with 2 speakers, which would mean it would be too loud for guests near them, if they were playing it loudly enough for people in the corners to hear.
To explain better how wireless speakers work, I normally place one in each corner of the room on the opposite side to where I am set up. If you click on the link below, you will hear how a guest who was sitting in that corner would hear the music. After a few seconds I turned it off so you would hear what that guest would hear without this speaker (just the two speakers near to me) and then turned it back on again.
Click to listen to sample: