I suspect they base this on volume. However, the lowish ceiling heights of 1980's and earlier basements may make things more difficult. More importantly for you is getting the room accoustics as good as possible. I suggest determining where your system will be placed and then sending your room layout/dimensions into one of the companies that specialize in room treatment and correction like Rives, Echobusters, Realtraps, etc. You may receive some good recommendations that you can incorporate into the remodel.
My unrealated recommendation is to not forget about dedicated lines, and think about the future. For example, if you have a stereo amp now, you may in the future have two monos that you want to postition next to your speakers - and they will each need their own power, that type of thing.
My unrealated recommendation is to not forget about dedicated lines, and think about the future. For example, if you have a stereo amp now, you may in the future have two monos that you want to postition next to your speakers - and they will each need their own power, that type of thing.