You connect one speaker up to your amp normally but the other speaker is connected out of phase.To do that you connect the speaker cable, at the speaker end, up differently.The red goes to black and the black to red at the speaker end. You then get one speaker pushing and one pulling.For some reason even when you turn up the amp, you get very little volume but the drivers are still working as normal.iI is perfectly safe and i have seen it mentioned in what hi fi? and hi fi choice many times over the years.I have also done it myself. The volume setting can affect how quickly you run in a speaker.At higher volume the drivers are moving further and this helps to loosen them up more quickly.The running in of the crossover and cable inside should take take the same time regardless of volume setting.