Well I ran into the reason why I have a back computer. My main laptop just crashed or stop working in the middle of setting up for a night at the bar. The program I use lets me have it on 2 laptops. So back up was there. Had to use my second controller as well but that is the point and the reason for being prepared.
In the past it would be a bad cd player or maybe a bad amp. In today’s world everything is a factor. Laptops, powered speakers, mixers, lighting, controllers and the list goes on. When we talk equipment & fixing these ideas, you have a lot to think about. No mater how you look at this, there is many things the modern dj has to think about. The biggest thing is that they have stable equipment that can do the job.