An 8-ohm system is best used for residential purposes and not for a commercial environment. With 8-ohm systems, you can have left, right, and center channels which are good when you are in a single room. If you’re listening to music, this provides the ability to hear the audio of the guitar on one channel, the drums on another channel, and vocals on a third channel. All of these channels are acoustically separated but combined at the same time. As mentioned, this is perfect for a residential space because a limited number of speakers are required.
70-volt systems are typically used for commercial environments, and are beneficial due to their multi-speaker usage, multi-volume control usage, smaller gage wire running great distances, and a single wire running parallel to the speakers. Resistance is not an issue as it would be with an 8-ohm system as compared to a 70-volt system that is more concerned with total wattage. Also, in a multi-room environment like a restaurant, you would not want the left and right channels to be separated because you would hear the guitar in one room and the drums in another. In addition, the audio quality of 70-volt systems can be equal to or even better than an 8-ohm system.